If a booking has been cancelled and you're not sure how, the best thing to do is check the activity log:
Go to the customer record
Click the Calendar tab
Click view booking on the cancelled booking
Click the activity log tab to see when and how the customer's booking was cancelled.
Or if the customer was removed from a group booking:
Find the booking in the calendar
Click the activity log tab to see when and how the customer was removed from the booking.
If the customer canceled their booking from a confirmation or reminder email
When the customer cancels, your business is notified by email.
When a booking is canceled, it remains in the customer record (as a canceled booking). Just go to the customer record and click bookings to see all bookings including cancelled ones.
You can prevent customers from canceling bookings by removing the cancellation link from confirmation and/or reminder emails.
Remove the cancellation link from confirmation emails from the Booking tools tab, under Customize your booking flow
Remove the cancellation link from reminder emails from the Email & SMS tab, under Manage reminders & followups, then by amending each reminder.
You can also control the required notice for cancelations from the online booking settings.
One of your business users could have canceled the booking
Bookings can be canceled by users who have access to the Appointedd back office. To prevent accidental deletion, two steps are required and an "are you sure" is asked before an internal cancelation can take place.
A booking can also be canceled through a synced external calendar. If you don't want bookings canceled in the external calendar to cancel in Appointedd, you can do this in your settings:
Go to the Connect tab
Click Sync your external calendar
Switch Cancel bookings in Appointedd when deleted in external calendar to OFF.