"Cancelling Appointment"

I was simply trying to cancel completely an out-patient appointment. I tried for over half an hour on telephone and on-line. I eventually gave up and called my already overwork Doctor's surgery and pleaded with them to cancel it for me. It should be so simple to do this either on line or by telephone - no options apparent just to cancel and appointment. Why? Totally frustrated by time wasted on something that should take a few minutes.