When the client receive an email after making the appointment, we may include a cancellation link. I suggest two improvements:

1. If someone clicks on the cancellation link, first a message shoud appear "Do you really want to cancel the appointment?" with the option of Yes and No. The appointment should be only cancelled if the client press Yes.
2. After making a cencellation, a special page shpuld be loaded (e.g. This way we can emphasize that the client irreversibly deleted the appointment)

Regards, Norbert