"Why have appointment times?"

It seems only a hospital can make you book an appointment, but this booking time means nothing. My child has follow-up appointments for urine tests and blood pressure. Somehow on the 2 occasions I have attended, this has taken well over 1 hour, one booking at 10:00 with actually leaving after 12:00. The next appointment is for 16:00, it is currently 17:11, when I have asked, I get told I am waiting for a doctor. I find this very frustrating, if the doctor is not available until 19:00, book the appointment for 19:00!!!! Or if they don't know, tell her when we arrive!!!