diff --git a/assets/js/backend_calendar_table_view.js b/assets/js/backend_calendar_table_view.js
index 6bd0204e..0f89f1ac 100755
--- a/assets/js/backend_calendar_table_view.js
+++ b/assets/js/backend_calendar_table_view.js
@@ -105,7 +105,7 @@ window.BackendCalendarTableView = window.BackendCalendarTableView || {};
 
                             // Add the provider breaks to the column.
                             var workingPlan = JSON.parse(provider.settings.working_plan);
-                            var day = date.toString('dddd').toLowerCase();
+                            var day = moment(date).format('dddd').toLowerCase();
                             if (workingPlan[day]) {
                                 var breaks = workingPlan[day].breaks;
                                 createBreaks($providerColumn, breaks);
@@ -505,8 +505,8 @@ window.BackendCalendarTableView = window.BackendCalendarTableView || {};
         }).appendTo('#calendar');
 
         $calendarView.data({
-            startDate: startDate.toString('yyyy-MM-dd'),
-            endDate: endDate.toString('yyyy-MM-dd')
+            startDate: moment(startDate).format('YYYY-MM-DD'),
+            endDate: moment(endDate).format('YYYY-MM-DD')
         });
 
         var $wrapper = $('<div/>').appendTo($calendarView);
@@ -846,7 +846,7 @@ window.BackendCalendarTableView = window.BackendCalendarTableView || {};
         var view = $calendar.fullCalendar('getView');
         var start = view.start.clone();
         var end = view.end.clone();
-        var selDayName = start.toDate().toString('dddd').toLowerCase();
+        var selDayName = start.format('dddd').toLowerCase();
         var selDayDate = start.format('YYYY-MM-DD');
         var calendarEventSource = [];
 
@@ -892,7 +892,7 @@ window.BackendCalendarTableView = window.BackendCalendarTableView || {};
             return;
         }
 
-        var workDateStart = moment(start.toDate().toString('yyyy-MM-dd') + ' ' + workingPlan[selDayName].start);
+        var workDateStart = moment(start.format('YYYY-MM-DD') + ' ' + workingPlan[selDayName].start);
 
         if (start < workDateStart) {
             unavailablePeriod = {
@@ -909,7 +909,7 @@ window.BackendCalendarTableView = window.BackendCalendarTableView || {};
         }
 
         // Add unavailable period after work ends.
-        var workDateEnd = moment(start.toDate().toString('yyyy-MM-dd') + ' ' + workingPlan[selDayName].end);
+        var workDateEnd = moment(start.format('YYYY-MM-DD') + ' ' + workingPlan[selDayName].end);
 
         if (end > workDateEnd) {
             var unavailablePeriod = {
@@ -930,8 +930,8 @@ window.BackendCalendarTableView = window.BackendCalendarTableView || {};
         var breakEnd;
 
         workingPlan[selDayName].breaks.forEach(function (currentBreak) {
-            breakStart = moment(start.toDate().toString('yyyy-MM-dd') + ' ' + currentBreak.start);
-            breakEnd = moment(start.toDate().toString('yyyy-MM-dd') + ' ' + currentBreak.end);
+            breakStart = moment(start.format('YYYY-MM-DD') + ' ' + currentBreak.start);
+            breakEnd = moment(start.format('YYYY-MM-DD') + ' ' + currentBreak.end);
 
             var unavailablePeriod = {
                 title: EALang.break,
@@ -1072,7 +1072,12 @@ window.BackendCalendarTableView = window.BackendCalendarTableView || {};
             });
 
             $event.html(
-                EALang.break + ' <span class="hour">' + eventDate.toString('HH:mm') + '</span> (' + eventDuration + "')"
+                EALang.break +
+                    ' <span class="hour">' +
+                    moment(eventDate).format('HH:mm') +
+                    '</span> (' +
+                    eventDuration +
+                    "')"
             );
 
             $event.data(entry);
@@ -1087,7 +1092,7 @@ window.BackendCalendarTableView = window.BackendCalendarTableView || {};
 
                 if (eventDate < cellDate) {
                     // Remove the hour from the event if it is the same as the row.
-                    if (eventDate.toString('HH:mm') === $(tr).prev().find('td').eq(0).text()) {
+                    if (moment(eventDate).format('HH:mm') === $(tr).prev().find('td').eq(0).text()) {
                         $event.find('.hour').remove();
                     }
 
@@ -1784,8 +1789,8 @@ window.BackendCalendarTableView = window.BackendCalendarTableView || {};
 
         var data = {
             csrfToken: GlobalVariables.csrfToken,
-            startDate: startDate.toString('yyyy-MM-dd'),
-            endDate: endDate.toString('yyyy-MM-dd')
+            startDate: moment(startDate).format('YYYY-MM-DD'),
+            endDate: moment(endDate).format('YYYY-MM-DD')
         };
 
         return $.ajax({
diff --git a/assets/js/backend_calendar_working_plan_exceptions_modal.js b/assets/js/backend_calendar_working_plan_exceptions_modal.js
index fccebf2c..722df779 100644
--- a/assets/js/backend_calendar_working_plan_exceptions_modal.js
+++ b/assets/js/backend_calendar_working_plan_exceptions_modal.js
@@ -66,8 +66,8 @@ window.BackendCalendarWorkingPlanExceptionsModal = window.BackendCalendarWorking
             }
 
             var workingPlanException = {
-                start: start.toString('HH:mm'),
-                end: end.toString('HH:mm'),
+                start: moment(start).format('HH:mm'),
+                end: moment(end).format('HH:mm'),
                 breaks: []
             };
 
@@ -88,12 +88,12 @@ window.BackendCalendarWorkingPlanExceptionsModal = window.BackendCalendarWorking
                     throw new Error('Provider could not be found: ' + providerId);
                 }
 
-                var selectedDate = date.toString('yyyy-MM-dd');
+                var selectedDate = moment(date).format('yyyy-MM-dd');
                 var workingPlanExceptions = JSON.parse(provider.settings.working_plan_exceptions);
 
                 workingPlanExceptions[selectedDate] = {
-                    start: start.toString('HH:mm'),
-                    end: end.toString('HH:mm'),
+                    start: moment(start).format('HH:mm'),
+                    end: moment(end).format('HH:mm'),
                     breaks: []
                 };
 
diff --git a/assets/js/frontend_book.js b/assets/js/frontend_book.js
index 7ff09a50..e0a18b9f 100644
--- a/assets/js/frontend_book.js
+++ b/assets/js/frontend_book.js
@@ -145,16 +145,17 @@ window.FrontendBook = window.FrontendBook || {};
             closeText: EALang.close,
 
             onSelect: function (dateText, instance) {
-                FrontendBookApi.getAvailableHours($(this).datepicker('getDate').toString('yyyy-MM-dd'));
+                FrontendBookApi.getAvailableHours(moment($(this).datepicker('getDate')).format('YYYY-MM-DD'));
                 FrontendBook.updateConfirmFrame();
             },
 
             onChangeMonthYear: function (year, month, instance) {
                 var currentDate = new Date(year, month - 1, 1);
+
                 FrontendBookApi.getUnavailableDates(
                     $('#select-provider').val(),
                     $('#select-service').val(),
-                    currentDate.toString('yyyy-MM-dd')
+                    moment(currentDate).format('YYYY-MM-DD')
                 );
             }
         });
@@ -220,7 +221,7 @@ window.FrontendBook = window.FrontendBook || {};
                 return;
             }
 
-            FrontendBookApi.getAvailableHours(date.toString('yyyy-MM-dd'));
+            FrontendBookApi.getAvailableHours(moment(date).format('YYYY-MM-DD'));
 
             FrontendBook.updateConfirmFrame();
         });
@@ -234,7 +235,7 @@ window.FrontendBook = window.FrontendBook || {};
             FrontendBookApi.getUnavailableDates(
                 $(this).val(),
                 $('#select-service').val(),
-                $('#select-date').datepicker('getDate').toString('yyyy-MM-dd')
+                moment($('#select-date').datepicker('getDate')).format('YYYY-MM-DD')
             );
             FrontendBook.updateConfirmFrame();
         });
@@ -274,7 +275,7 @@ window.FrontendBook = window.FrontendBook || {};
             FrontendBookApi.getUnavailableDates(
                 $('#select-provider').val(),
                 $(this).val(),
-                $('#select-date').datepicker('getDate').toString('yyyy-MM-dd')
+                moment($('#select-date').datepicker('getDate')).format('YYYY-MM-DD')
             );
             FrontendBook.updateConfirmFrame();
             updateServiceDescription(serviceId);
@@ -671,7 +672,7 @@ window.FrontendBook = window.FrontendBook || {};
             start_datetime:
                 moment($('#select-date').datepicker('getDate')).format('YYYY-MM-DD') +
                 ' ' +
-                moment($('.selected-hour').data('value') || '').format('HH:mm') +
+                moment($('.selected-hour').data('value'), 'HH:mm').format('HH:mm') +
                 ':00',
             end_datetime: calculateEndDatetime(),
             notes: $('#notes').val(),
diff --git a/assets/js/frontend_book_api.js b/assets/js/frontend_book_api.js
index 4fbd7aeb..2c1cf044 100755
--- a/assets/js/frontend_book_api.js
+++ b/assets/js/frontend_book_api.js
@@ -272,15 +272,16 @@ window.FrontendBookApi = window.FrontendBookApi || {};
         processingUnavailabilities = true;
 
         // Select first enabled date.
-        var selectedDate = moment(selectedDateString).toDate();
-        var numberOfDays = moment(selectedDateString).daysInMonth();
+        var selectedDateMoment = moment(selectedDateString);
+        var selectedDate = selectedDateMoment.toDate();
+        var numberOfDays = selectedDateMoment.daysInMonth();
 
         if (setDate && !GlobalVariables.manageMode) {
             for (var i = 1; i <= numberOfDays; i++) {
                 var currentDate = new Date(selectedDate.getFullYear(), selectedDate.getMonth(), i);
-                if (unavailableDates.indexOf(currentDate.toString('yyyy-MM-dd')) === -1) {
+                if (unavailableDates.indexOf(moment(currentDate).format('YYYY-MM-DD')) === -1) {
                     $('#select-date').datepicker('setDate', currentDate);
-                    FrontendBookApi.getAvailableHours(currentDate.toString('yyyy-MM-dd'));
+                    FrontendBookApi.getAvailableHours(moment(currentDate).format('YYYY-MM-DD'));
                     break;
                 }
             }
@@ -293,8 +294,8 @@ window.FrontendBookApi = window.FrontendBookApi || {};
 
         // Grey out unavailable dates.
         $('#select-date .ui-datepicker-calendar td:not(.ui-datepicker-other-month)').each(function (index, td) {
-            selectedDate.set({day: index + 1});
-            if (unavailableDates.indexOf(selectedDate.toString('yyyy-MM-dd')) !== -1) {
+            selectedDateMoment.set({day: index + 1});
+            if (unavailableDates.indexOf(selectedDateMoment.format('YYYY-MM-DD')) !== -1) {
                 $(td).addClass('ui-datepicker-unselectable ui-state-disabled');
             }
         });
diff --git a/assets/js/working_plan_exceptions_modal.js b/assets/js/working_plan_exceptions_modal.js
index e40c34dc..8c55f083 100644
--- a/assets/js/working_plan_exceptions_modal.js
+++ b/assets/js/working_plan_exceptions_modal.js
@@ -83,11 +83,11 @@ $(function () {
             return;
         }
 
-        var date = $date.datepicker('getDate').toString('yyyy-MM-dd');
+        var date = moment($date.datepicker('getDate')).format('YYYY-MM-DD');
 
         var workingPlanException = {
-            start: $start.datetimepicker('getDate').toString('HH:mm'),
-            end: $end.datetimepicker('getDate').toString('HH:mm'),
+            start: moment($start.datetimepicker('getDate')).format('HH:mm'),
+            end: moment($end.datetimepicker('getDate')).format('HH:mm'),
             breaks: getBreaks()
         };
 
@@ -170,11 +170,11 @@ $(function () {
             'html': [
                 $('<td/>', {
                     'class': 'working-plan-exceptions-break-start editable',
-                    'text': moment(breakPeriod.start, 'HH:mm').toString(timeFormat)
+                    'text': moment(breakPeriod.start, 'HH:mm').format(timeFormat)
                 }),
                 $('<td/>', {
                     'class': 'working-plan-exceptions-break-end editable',
-                    'text': moment(breakPeriod.end, 'HH:mm').toString(timeFormat)
+                    'text': moment(breakPeriod.end, 'HH:mm').format(timeFormat)
                 }),
                 $('<td/>', {
                     'html': [