"Appointments"

I have been going for a couple of years and it as been fine. But then i had an exam on my appointment date, so as usual i rang up and there was no answer which happens all the time so i left a message asking to rearange my appointment. I never heard back from the orthodontist and still to this day have not recieved an appointment and it has been a few months now. i still keep ringing and leaving messages but never get an appointment, also to top it off i went down to day and the receptionist said she cant make the appointment, but my orthodontist was not in today. What am i meant to do?