diff --git a/src/application/controllers/Appointments.php b/src/application/controllers/Appointments.php
index ffebfb44..a61509b6 100755
--- a/src/application/controllers/Appointments.php
+++ b/src/application/controllers/Appointments.php
@@ -220,7 +220,7 @@ class Appointments extends CI_Controller {
                 {
                     $email->sendDeleteAppointment($appointment, $provider,
                         $service, $customer, $company_settings, new Email($provider['email']),
-                        new Text($_POST['cancel_reason']));
+                        new Text($this->input->post('cancel_reason')));
                 }
 
                 $send_customer = filter_var($this->settings_model->get_setting('customer_notifications'),
@@ -230,7 +230,7 @@ class Appointments extends CI_Controller {
                 {
                     $email->sendDeleteAppointment($appointment, $provider,
                         $service, $customer, $company_settings, new Email($customer['email']),
-                        new Text($_POST['cancel_reason']));
+                        new Text($this->input->post('cancel_reason')));
                 }
 
             } catch (Exception $exc)
@@ -321,7 +321,7 @@ class Appointments extends CI_Controller {
         try
         {
             // Do not continue if there was no provider selected (more likely there is no provider in the system).
-            if (empty($_POST['provider_id']))
+            if (empty($this->input->post('provider_id')))
             {
                 echo json_encode([]);
                 return;
@@ -329,36 +329,36 @@ class Appointments extends CI_Controller {
 
             // If manage mode is TRUE then the following we should not consider the selected
             // appointment when calculating the available time periods of the provider.
-            $exclude_appointments = ($_POST['manage_mode'] === 'true')
-                ? [$_POST['appointment_id']]
+            $exclude_appointments = ($this->input->post('manage_mode') === 'true')
+                ? [$this->input->post('appointment_id')]
                 : [];
 
             // If the user has selected the "any-provider" option then we will need to search
             // for an available provider that will provide the requested service.
-            if ($_POST['provider_id'] === ANY_PROVIDER)
+            if ($this->input->post('provider_id') === ANY_PROVIDER)
             {
-                $_POST['provider_id'] = $this->_search_any_provider($_POST['service_id'], $_POST['selected_date']);
-                if ($_POST['provider_id'] === NULL)
+                $_POST['provider_id'] = $this->_search_any_provider($this->input->post('service_id'), $this->input->post('selected_date'));
+                if ($this->input->post('provider_id') === NULL)
                 {
                     echo json_encode([]);
                     return;
                 }
             }
 
-            $availabilities_type = $this->services_model->get_value('availabilities_type', $_POST['service_id']);
-            $attendants_number = $this->services_model->get_value('attendants_number', $_POST['service_id']);
+            $availabilities_type = $this->services_model->get_value('availabilities_type', $this->input->post('service_id'));
+            $attendants_number = $this->services_model->get_value('attendants_number', $this->input->post('service_id'));
 
-            $empty_periods = $this->_get_provider_available_time_periods($_POST['provider_id'],
-                $_POST['selected_date'], $exclude_appointments);
+            $empty_periods = $this->_get_provider_available_time_periods($this->input->post('provider_id'),
+                $this->input->post('selected_date'), $exclude_appointments);
 
-            $available_hours = $this->_calculate_available_hours($empty_periods, $_POST['selected_date'],
-                $_POST['service_duration'], filter_var($_POST['manage_mode'], FILTER_VALIDATE_BOOLEAN),
+            $available_hours = $this->_calculate_available_hours($empty_periods, $this->input->post('selected_date'),
+                $this->input->post('service_duration'), filter_var($this->input->post('manage_mode'), FILTER_VALIDATE_BOOLEAN),
                 $availabilities_type);
 
             if ($attendants_number > 1)
             {
-                $this->_get_multiple_attendants_hours($available_hours, $attendants_number, $_POST['service_id'],
-                    $_POST['selected_date']);
+                $this->_get_multiple_attendants_hours($available_hours, $attendants_number, $this->input->post('service_id'),
+                    $this->input->post('selected_date'));
             }
 
             echo json_encode($available_hours);
@@ -380,7 +380,7 @@ class Appointments extends CI_Controller {
     {
         try
         {
-            $post_data = $_POST['post_data']; // alias
+            $post_data = $this->input->post('post_data'); // alias
             $post_data['manage_mode'] = filter_var($post_data['manage_mode'], FILTER_VALIDATE_BOOLEAN);
 
             $this->load->model('appointments_model');
@@ -391,7 +391,7 @@ class Appointments extends CI_Controller {
 
             // Validate the CAPTCHA string.
             if ($this->settings_model->get_setting('require_captcha') === '1'
-                && $this->session->userdata('captcha_phrase') !== $_POST['captcha'])
+                && $this->session->userdata('captcha_phrase') !== $this->input->post('captcha'))
             {
                 echo json_encode([
                     'captcha_verification' => FALSE,
@@ -406,8 +406,8 @@ class Appointments extends CI_Controller {
                 throw new Exception($this->lang->line('requested_hour_is_unavailable'));
             }
 
-            $appointment = $_POST['post_data']['appointment'];
-            $customer = $_POST['post_data']['customer'];
+            $appointment = $this->input->post('post_data')['appointment'];
+            $customer = $this->input->post('post_data')['customer'];
 
             if ($this->customers_model->exists($customer))
             {
@@ -617,7 +617,7 @@ class Appointments extends CI_Controller {
         $this->load->model('services_model');
         $this->load->model('appointments_model');
 
-        $appointment = $_POST['post_data']['appointment'];
+        $appointment = $this->input->post('post_data')['appointment'];
 
         $service_duration = $this->services_model->get_value('duration', $appointment['id_services']);
 
@@ -646,7 +646,7 @@ class Appointments extends CI_Controller {
         {
             $appointment['id_users_provider'] = $this->_search_any_provider($appointment['id_services'],
                 date('Y-m-d', strtotime($appointment['start_datetime'])));
-            $_POST['post_data']['appointment']['id_users_provider'] = $appointment['id_users_provider'];
+            $this->input->post('post_data')['appointment']['id_users_provider'] = $appointment['id_users_provider'];
             return TRUE; // The selected provider is always available.
         }
 
diff --git a/src/application/controllers/Backend_api.php b/src/application/controllers/Backend_api.php
index 0ec9ce86..b4d0c7f5 100644
--- a/src/application/controllers/Backend_api.php
+++ b/src/application/controllers/Backend_api.php
@@ -75,8 +75,8 @@ class Backend_api extends CI_Controller {
             $this->load->model('services_model');
             $this->load->model('providers_model');
 
-            $startDate = $_POST['startDate'] . ' 00:00:00';
-            $endDate = $_POST['endDate'] . ' 23:59:59';
+            $startDate = $this->input->post('startDate') . ' 00:00:00';
+            $endDate = $this->input->post('endDate') . ' 23:59:59';
 
             $response = [
                 'appointments' => $this->appointments_model->get_batch([
@@ -174,7 +174,7 @@ class Backend_api extends CI_Controller {
                 throw new Exception('You do not have the required privileges for this task.');
             }
 
-            if ( ! isset($_POST['filter_type']))
+            if ( ! $this->input->post('filter_type'))
             {
                 echo json_encode(['appointments' => []]);
                 return;
@@ -185,7 +185,7 @@ class Backend_api extends CI_Controller {
             $this->load->model('services_model');
             $this->load->model('customers_model');
 
-            if ($_POST['filter_type'] == FILTER_TYPE_PROVIDER)
+            if ($this->input->post('filter_type') == FILTER_TYPE_PROVIDER)
             {
                 $where_id = 'id_users_provider';
             } else
@@ -195,9 +195,9 @@ class Backend_api extends CI_Controller {
 
             // Get appointments
             $where_clause = [
-                $where_id => $_POST['record_id'],
-                //'start_datetime >=' => $_POST['start_date'],
-                //'end_datetime <=' => $_POST['end_date'],
+                $where_id => $this->input->post('record_id'),
+                //'start_datetime >=' => $this->input->post('start_date'),
+                //'end_datetime <=' => $this->input->post('end_date'),
                 'is_unavailable' => FALSE
             ];
 
@@ -211,12 +211,12 @@ class Backend_api extends CI_Controller {
             }
 
             // Get unavailable periods (only for provider).
-            if ($_POST['filter_type'] == FILTER_TYPE_PROVIDER)
+            if ($this->input->post('filter_type') == FILTER_TYPE_PROVIDER)
             {
                 $where_clause = [
-                    $where_id => $_POST['record_id'],
-                    //'start_datetime >=' => $_POST['start_date'],
-                    //'end_datetime <=' => $_POST['end_date'],
+                    $where_id => $this->input->post('record_id'),
+                    //'start_datetime >=' => $this->input->post('start_date'),
+                    //'end_datetime <=' => $this->input->post('end_date'),
                     'is_unavailable' => TRUE
                 ];
 
@@ -252,9 +252,9 @@ class Backend_api extends CI_Controller {
             $this->load->model('settings_model');
 
             // :: SAVE CUSTOMER CHANGES TO DATABASE
-            if (isset($_POST['customer_data']))
+            if ($this->input->post('customer_data'))
             {
-                $customer = json_decode($_POST['customer_data'], TRUE);
+                $customer = json_decode($this->input->post('customer_data'), TRUE);
 
                 $REQUIRED_PRIV = ( ! isset($customer['id']))
                     ? $this->privileges[PRIV_CUSTOMERS]['add']
@@ -268,9 +268,9 @@ class Backend_api extends CI_Controller {
             }
 
             // :: SAVE APPOINTMENT CHANGES TO DATABASE
-            if (isset($_POST['appointment_data']))
+            if ($this->input->post('appointment_data'))
             {
-                $appointment = json_decode($_POST['appointment_data'], TRUE);
+                $appointment = json_decode($this->input->post('appointment_data'), TRUE);
 
                 $REQUIRED_PRIV = ( ! isset($appointment['id']))
                     ? $this->privileges[PRIV_APPOINTMENTS]['add']
@@ -417,7 +417,7 @@ class Backend_api extends CI_Controller {
                 throw new Exception('You do not have the required privileges for this task.');
             }
 
-            if ( ! isset($_POST['appointment_id']))
+            if ( ! $this->input->post('appointment_id'))
             {
                 throw new Exception('No appointment id provided.');
             }
@@ -429,7 +429,7 @@ class Backend_api extends CI_Controller {
             $this->load->model('services_model');
             $this->load->model('settings_model');
 
-            $appointment = $this->appointments_model->get_row($_POST['appointment_id']);
+            $appointment = $this->appointments_model->get_row($this->input->post('appointment_id'));
             $provider = $this->providers_model->get_row($appointment['id_users_provider']);
             $customer = $this->customers_model->get_row($appointment['id_users_customer']);
             $service = $this->services_model->get_row($appointment['id_services']);
@@ -441,7 +441,7 @@ class Backend_api extends CI_Controller {
             ];
 
             // :: DELETE APPOINTMENT RECORD FROM DATABASE
-            $this->appointments_model->delete($_POST['appointment_id']);
+            $this->appointments_model->delete($this->input->post('appointment_id'));
 
             // :: SYNC DELETE WITH GOOGLE CALENDAR
             if ($appointment['id_google_calendar'] != NULL)
@@ -477,7 +477,7 @@ class Backend_api extends CI_Controller {
                 {
                     $email->sendDeleteAppointment($appointment, $provider,
                         $service, $customer, $company_settings, new Email($provider['email']),
-                        new Text($_POST['delete_reason']));
+                        new Text($this->input->post('delete_reason')));
                 }
 
                 $send_customer = $this->settings_model->get_setting('customer_notifications');
@@ -486,7 +486,7 @@ class Backend_api extends CI_Controller {
                 {
                     $email->sendDeleteAppointment($appointment, $provider,
                         $service, $customer, $company_settings, new Email($customer['email']),
-                        new Text($_POST['delete_reason']));
+                        new Text($this->input->post('delete_reason')));
                 }
             } catch (Exception $exc)
             {
@@ -525,22 +525,19 @@ class Backend_api extends CI_Controller {
     {
         try
         {
-            if ( ! isset($_POST['provider_id']))
+            if ( ! $this->input->post('provider_id'))
             {
                 throw new Exception('Provider id not specified.');
             }
 
             if ($this->privileges[PRIV_USERS]['edit'] == FALSE
-                && $this->session->userdata('user_id') != $_POST['provider_id'])
+                && $this->session->userdata('user_id') != $this->input->post('provider_id'))
             {
                 throw new Exception('You do not have the required privileges for this task.');
             }
 
-            $this->load->model('providers_model');
-            $this->load->model('appointments_model');
-            $this->providers_model->set_setting('google_sync', FALSE, $_POST['provider_id']);
-            $this->providers_model->set_setting('google_token', NULL, $_POST['provider_id']);
-            $this->appointments_model->clear_google_sync_ids($_POST['provider_id']);
+            $this->load->model('providers_model');$this->load->model('appointments_model');$this->providers_model->set_setting('google_sync', FALSE, $this->input->post('provider_id'));
+            $this->providers_model->set_setting('google_token', NULL, $this->input->post('provider_id'));$this->appointments_model->clear_google_sync_ids($this->input->post('provider_id'));
 
             echo json_encode(AJAX_SUCCESS);
 
@@ -575,7 +572,7 @@ class Backend_api extends CI_Controller {
             $this->load->model('providers_model');
             $this->load->model('customers_model');
 
-            $key = $this->db->escape_str($_POST['key']);
+            $key = $this->db->escape_str($this->input->post('key'));
             $key = strtoupper($key);
 
             $where_clause =
@@ -597,10 +594,8 @@ class Backend_api extends CI_Controller {
 
                 foreach ($appointments as &$appointment)
                 {
-                    $appointment['service'] = $this->services_model
-                        ->get_row($appointment['id_services']);
-                    $appointment['provider'] = $this->providers_model
-                        ->get_row($appointment['id_users_provider']);
+                    $appointment['service'] = $this->services_model->get_row($appointment['id_services']);
+                    $appointment['provider'] = $this->providers_model->get_row($appointment['id_users_provider']);
                 }
 
                 $customer['appointments'] = $appointments;
@@ -628,7 +623,7 @@ class Backend_api extends CI_Controller {
         try
         {
             // Check privileges
-            $unavailable = json_decode($_POST['unavailable'], TRUE);
+            $unavailable = json_decode($this->input->post('unavailable'), TRUE);
 
             $REQUIRED_PRIV = ( ! isset($unavailable['id']))
                 ? $this->privileges[PRIV_APPOINTMENTS]['add']
@@ -713,7 +708,7 @@ class Backend_api extends CI_Controller {
             $this->load->model('appointments_model');
             $this->load->model('providers_model');
 
-            $unavailable = $this->appointments_model->get_row($_POST['unavailable_id']);
+            $unavailable = $this->appointments_model->get_row($this->input->post('unavailable_id'));
             $provider = $this->providers_model->get_row($unavailable['id_users_provider']);
 
             // Delete unavailable
@@ -765,7 +760,7 @@ class Backend_api extends CI_Controller {
         try
         {
             $this->load->model('customers_model');
-            $customer = json_decode($_POST['customer'], TRUE);
+            $customer = json_decode($this->input->post('customer'), TRUE);
 
             $REQUIRED_PRIV = ( ! isset($customer['id']))
                 ? $this->privileges[PRIV_CUSTOMERS]['add']
@@ -805,7 +800,7 @@ class Backend_api extends CI_Controller {
             }
 
             $this->load->model('customers_model');
-            $this->customers_model->delete($_POST['customer_id']);
+            $this->customers_model->delete($this->input->post('customer_id'));
             echo json_encode(AJAX_SUCCESS);
         } catch (Exception $exc)
         {
@@ -827,7 +822,7 @@ class Backend_api extends CI_Controller {
         try
         {
             $this->load->model('services_model');
-            $service = json_decode($_POST['service'], TRUE);
+            $service = json_decode($this->input->post('service'), TRUE);
 
             $REQUIRED_PRIV = ( ! isset($service['id']))
                 ? $this->privileges[PRIV_SERVICES]['add']
@@ -867,7 +862,7 @@ class Backend_api extends CI_Controller {
             }
 
             $this->load->model('services_model');
-            $result = $this->services_model->delete($_POST['service_id']);
+            $result = $this->services_model->delete($this->input->post('service_id'));
             echo ($result) ? json_encode(AJAX_SUCCESS) : json_encode(AJAX_FAILURE);
         } catch (Exception $exc)
         {
@@ -896,7 +891,7 @@ class Backend_api extends CI_Controller {
             }
 
             $this->load->model('services_model');
-            $key = $this->db->escape_str($_POST['key']);
+            $key = $this->db->escape_str($this->input->post('key'));
             $where =
                 '(name LIKE "%' . $key . '%" OR duration LIKE "%' . $key . '%" OR ' .
                 'price LIKE "%' . $key . '%" OR currency LIKE "%' . $key . '%" OR ' .
@@ -924,7 +919,7 @@ class Backend_api extends CI_Controller {
         try
         {
             $this->load->model('services_model');
-            $category = json_decode($_POST['category'], TRUE);
+            $category = json_decode($this->input->post('category'), TRUE);
 
             $REQUIRED_PRIV = ( ! isset($category['id']))
                 ? $this->privileges[PRIV_SERVICES]['add']
@@ -962,7 +957,7 @@ class Backend_api extends CI_Controller {
             }
 
             $this->load->model('services_model');
-            $result = $this->services_model->delete_category($_POST['category_id']);
+            $result = $this->services_model->delete_category($this->input->post('category_id'));
             echo ($result) ? json_encode(AJAX_SUCCESS) : json_encode(AJAX_FAILURE);
         } catch (Exception $exc)
         {
@@ -991,7 +986,7 @@ class Backend_api extends CI_Controller {
             }
 
             $this->load->model('services_model');
-            $key = $this->db->escape_str($_POST['key']);
+            $key = $this->db->escape_str($this->input->post('key'));
             $where = '(name LIKE "%' . $key . '%" OR description LIKE "%' . $key . '%")';
             $categories = $this->services_model->get_all_categories($where);
             echo json_encode($categories);
@@ -1022,7 +1017,7 @@ class Backend_api extends CI_Controller {
             }
 
             $this->load->model('admins_model');
-            $key = $this->db->escape_str($_POST['key']);
+            $key = $this->db->escape_str($this->input->post('key'));
             $where =
                 '(first_name LIKE "%' . $key . '%" OR last_name LIKE "%' . $key . '%" ' .
                 'OR email LIKE "%' . $key . '%" OR mobile_number LIKE "%' . $key . '%" ' .
@@ -1054,7 +1049,7 @@ class Backend_api extends CI_Controller {
         try
         {
             $this->load->model('admins_model');
-            $admin = json_decode($_POST['admin'], TRUE);
+            $admin = json_decode($this->input->post('admin'), TRUE);
 
             $REQUIRED_PRIV = ( ! isset($admin['id']))
                 ? $this->privileges[PRIV_USERS]['add']
@@ -1099,7 +1094,7 @@ class Backend_api extends CI_Controller {
             }
 
             $this->load->model('admins_model');
-            $result = $this->admins_model->delete($_POST['admin_id']);
+            $result = $this->admins_model->delete($this->input->post('admin_id'));
             echo ($result) ? json_encode(AJAX_SUCCESS) : json_encode(AJAX_FAILURE);
         } catch (Exception $exc)
         {
@@ -1128,7 +1123,7 @@ class Backend_api extends CI_Controller {
             }
 
             $this->load->model('providers_model');
-            $key = $this->db->escape_str($_POST['key']);
+            $key = $this->db->escape_str($this->input->post('key'));
             $where =
                 '(first_name LIKE "%' . $key . '%" OR last_name LIKE "%' . $key . '%" ' .
                 'OR email LIKE "%' . $key . '%" OR mobile_number LIKE "%' . $key . '%" ' .
@@ -1160,7 +1155,7 @@ class Backend_api extends CI_Controller {
         try
         {
             $this->load->model('providers_model');
-            $provider = json_decode($_POST['provider'], TRUE);
+            $provider = json_decode($this->input->post('provider'), TRUE);
 
             $REQUIRED_PRIV = ( ! isset($provider['id']))
                 ? $this->privileges[PRIV_USERS]['add']
@@ -1211,7 +1206,7 @@ class Backend_api extends CI_Controller {
             }
 
             $this->load->model('providers_model');
-            $result = $this->providers_model->delete($_POST['provider_id']);
+            $result = $this->providers_model->delete($this->input->post('provider_id'));
             echo ($result) ? json_encode(AJAX_SUCCESS) : json_encode(AJAX_FAILURE);
         } catch (Exception $exc)
         {
@@ -1240,7 +1235,7 @@ class Backend_api extends CI_Controller {
             }
 
             $this->load->model('secretaries_model');
-            $key = $this->db->escape_str($_POST['key']);
+            $key = $this->db->escape_str($this->input->post('key'));
             $where =
                 '(first_name LIKE "%' . $key . '%" OR last_name LIKE "%' . $key . '%" ' .
                 'OR email LIKE "%' . $key . '%" OR mobile_number LIKE "%' . $key . '%" ' .
@@ -1272,7 +1267,7 @@ class Backend_api extends CI_Controller {
         try
         {
             $this->load->model('secretaries_model');
-            $secretary = json_decode($_POST['secretary'], TRUE);
+            $secretary = json_decode($this->input->post('secretary'), TRUE);
 
             $REQUIRED_PRIV = ( ! isset($secretary['id']))
                 ? $this->privileges[PRIV_USERS]['add']
@@ -1315,7 +1310,7 @@ class Backend_api extends CI_Controller {
             }
 
             $this->load->model('secretaries_model');
-            $result = $this->secretaries_model->delete($_POST['secretary_id']);
+            $result = $this->secretaries_model->delete($this->input->post('secretary_id'));
             echo ($result) ? json_encode(AJAX_SUCCESS) : json_encode(AJAX_FAILURE);
         } catch (Exception $exc)
         {
@@ -1340,25 +1335,25 @@ class Backend_api extends CI_Controller {
     {
         try
         {
-            if ($_POST['type'] == SETTINGS_SYSTEM)
+            if ($this->input->post('type') == SETTINGS_SYSTEM)
             {
                 if ($this->privileges[PRIV_SYSTEM_SETTINGS]['edit'] == FALSE)
                 {
                     throw new Exception('You do not have the required privileges for this task.');
                 }
                 $this->load->model('settings_model');
-                $settings = json_decode($_POST['settings'], TRUE);
+                $settings = json_decode($this->input->post('settings'), TRUE);
                 $this->settings_model->save_settings($settings);
             } else
             {
-                if ($_POST['type'] == SETTINGS_USER)
+                if ($this->input->post('type') == SETTINGS_USER)
                 {
                     if ($this->privileges[PRIV_USER_SETTINGS]['edit'] == FALSE)
                     {
                         throw new Exception('You do not have the required privileges for this task.');
                     }
                     $this->load->model('user_model');
-                    $this->user_model->save_settings(json_decode($_POST['settings'], TRUE));
+                    $this->user_model->save_settings(json_decode($this->input->post('settings'), TRUE));
                 }
             }
 
@@ -1386,7 +1381,7 @@ class Backend_api extends CI_Controller {
             // We will only use the function in the admins_model because it is sufficient
             // for the rest user types for now (providers, secretaries).
             $this->load->model('admins_model');
-            $is_valid = $this->admins_model->validate_username($_POST['username'], $_POST['user_id']);
+            $is_valid = $this->admins_model->validate_username($this->input->post('username'), $this->input->post('user_id'));
             echo json_encode($is_valid);
         } catch (Exception $exc)
         {
@@ -1413,7 +1408,7 @@ class Backend_api extends CI_Controller {
             $found = FALSE;
             foreach ($this->config->item('available_languages') as $lang)
             {
-                if ($lang == $_POST['language'])
+                if ($lang == $this->input->post('language'))
                 {
                     $found = TRUE;
                     break;
@@ -1422,11 +1417,11 @@ class Backend_api extends CI_Controller {
 
             if ( ! $found)
             {
-                throw new Exception('Translations for the given language does not exist (' . $_POST['language'] . ').');
+                throw new Exception('Translations for the given language does not exist (' . $this->input->post('language') . ').');
             }
 
-            $this->session->set_userdata('language', $_POST['language']);
-            $this->config->set_item('language', $_POST['language']);
+            $this->session->set_userdata('language', $this->input->post('language'));
+            $this->config->set_item('language', $this->input->post('language'));
 
             echo json_encode(AJAX_SUCCESS);
 
@@ -1455,16 +1450,16 @@ class Backend_api extends CI_Controller {
             $this->load->library('google_sync');
             $this->load->model('providers_model');
 
-            if ( ! isset($_POST['provider_id']))
+            if ( ! $this->input->post('provider_id'))
             {
                 throw new Exception('Provider id is required in order to fetch the google calendars.');
             }
 
             // Check if selected provider has sync enabled.
-            $google_sync = $this->providers_model->get_setting('google_sync', $_POST['provider_id']);
+            $google_sync = $this->providers_model->get_setting('google_sync', $this->input->post('provider_id'));
             if ($google_sync)
             {
-                $google_token = json_decode($this->providers_model->get_setting('google_token', $_POST['provider_id']));
+                $google_token = json_decode($this->providers_model->get_setting('google_token', $this->input->post('provider_id')));
                 $this->google_sync->refresh_token($google_token->refresh_token);
                 $calendars = $this->google_sync->get_google_calendars();
                 echo json_encode($calendars);
@@ -1495,14 +1490,14 @@ class Backend_api extends CI_Controller {
         try
         {
             if ($this->privileges[PRIV_USERS]['edit'] == FALSE
-                && $this->session->userdata('user_id') != $_POST['provider_id'])
+                && $this->session->userdata('user_id') != $this->input->post('provider_id'))
             {
                 throw new Exception('You do not have the required privileges for this task.');
             }
 
             $this->load->model('providers_model');
-            $result = $this->providers_model->set_setting('google_calendar', $_POST['calendar_id'],
-                $_POST['provider_id']);
+            $result = $this->providers_model->set_setting('google_calendar', $this->input->post('calendar_id'),
+                $this->input->post('provider_id'));
             echo json_encode(($result) ? AJAX_SUCCESS : AJAX_FAILURE);
 
         } catch (Exception $exc)
diff --git a/src/application/controllers/Google.php b/src/application/controllers/Google.php
index 6d698459..3b4e78bc 100644
--- a/src/application/controllers/Google.php
+++ b/src/application/controllers/Google.php
@@ -59,10 +59,10 @@ class Google extends CI_Controller {
      */
     public function oauth_callback()
     {
-        if (isset($_GET['code']))
+        if ($this->input->get('code'))
         {
             $this->load->library('Google_sync');
-            $token = $this->google_sync->authenticate($_GET['code']);
+            $token = $this->google_sync->authenticate($this->input->get('code'));
 
             // Store the token into the database for future reference.
             if (isset($_SESSION['oauth_provider_id']))
diff --git a/src/application/controllers/Installation.php b/src/application/controllers/Installation.php
index ce6e42b2..197b0d9e 100644
--- a/src/application/controllers/Installation.php
+++ b/src/application/controllers/Installation.php
@@ -92,7 +92,7 @@ class Installation extends CI_Controller {
 
             // Insert admin
             $this->load->model('admins_model');
-            $admin = json_decode($_POST['admin'], TRUE);
+            $admin = json_decode($this->input->post('admin'), TRUE);
             $admin['settings']['username'] = $admin['username'];
             $admin['settings']['password'] = $admin['password'];
             $admin['settings']['calendar_view'] = CALENDAR_VIEW_DEFAULT;
@@ -107,7 +107,7 @@ class Installation extends CI_Controller {
 
             // Save company settings
             $this->load->model('settings_model');
-            $company = json_decode($_POST['company'], TRUE);
+            $company = json_decode($this->input->post('company'), TRUE);
             $this->settings_model->set_setting('company_name', $company['company_name']);
             $this->settings_model->set_setting('company_email', $company['company_email']);
             $this->settings_model->set_setting('company_link', $company['company_link']);
diff --git a/src/application/controllers/User.php b/src/application/controllers/User.php
index 54e2b8a1..db31d4e5 100644
--- a/src/application/controllers/User.php
+++ b/src/application/controllers/User.php
@@ -121,13 +121,13 @@ class User extends CI_Controller {
     {
         try
         {
-            if ( ! isset($_POST['username']) || ! isset($_POST['password']))
+            if ( ! $this->input->post('username') || ! $this->input->post('password'))
             {
                 throw new Exception('Invalid credentials given!');
             }
 
             $this->load->model('user_model');
-            $user_data = $this->user_model->check_login($_POST['username'], $_POST['password']);
+            $user_data = $this->user_model->check_login($this->input->post('username'), $this->input->post('password'));
 
             if ($user_data)
             {
@@ -159,7 +159,7 @@ class User extends CI_Controller {
     {
         try
         {
-            if ( ! isset($_POST['username']) || ! isset($_POST['email']))
+            if ( ! $this->input->post('username') || ! $this->input->post('email'))
             {
                 throw new Exception('You must enter a valid username and email address in '
                     . 'order to get a new password!');
@@ -168,7 +168,7 @@ class User extends CI_Controller {
             $this->load->model('user_model');
             $this->load->model('settings_model');
 
-            $new_password = $this->user_model->regenerate_password($_POST['username'], $_POST['email']);
+            $new_password = $this->user_model->regenerate_password($this->input->post('username'), $this->input->post('email'));
 
             if ($new_password != FALSE)
             {
@@ -180,7 +180,7 @@ class User extends CI_Controller {
                     'company_email' => $this->settings_model->get_setting('company_email')
                 ];
 
-                $email->sendPassword(new NonEmptyText($new_password), new Email($_POST['email']), $company_settings);
+                $email->sendPassword(new NonEmptyText($new_password), new Email($this->input->post('email')), $company_settings);
             }
 
             echo ($new_password != FALSE) ? json_encode(AJAX_SUCCESS) : json_encode(AJAX_FAILURE);