Some appointment-booking offices give you an email option - as long as you give them minimum 48-hours notice. But not many do have that facility.
Appointments handled by booking offices clearly don't have a sufficient number of staff - I don't think I have ever been able to get through to cancel or change an appointment.
What I dislike is when you are asked to leave your name and telephone number - we "aim to get back to you with xx hours". Which means remembering to cart your mobile around with you for the rest of the day.
On one occasion, I spoke to someone who said they would confirm a particular appointment, but they didn't know "when". Fine, said I - can you leave a message if I don't happen to pick-up. "No, we are not allowed to leave messages because of patient-privacy". I argued that it was my mobile which is answered by me. It cut no ice. They did call back - I was in the shower. They did leave a message - for me to call them back again. Which I did... only to be told by recorded voice that all the lines were "busy right now" so please leave your name and telephone number and we will get back to you...
It's a bloody stupid system.