I am registered with a fairly large GP surgery where there are about 8 doctors working each day and they run the system of book on the day appointments.
Phones lines open at 08.30am and yesterday I called them and redialled and redialled until I finally got through at 08.37am to be told there were no appointments left for any of the doctors!!
"Try again tomorrow" she said far too chirping for my liking.
So I try again this morning and despite getting through at 08.34am I was told that yet again, all the appointments had gone. It was only four minutes since the phone line had opened!!
She said, "Try again tomorrow" 
I'm back at work tomorrow though so there's no point anyway.
I understand the book on the day system and I do agree with it but I still feel annoyed 
Pre-bookable appointments are available but it is a wait of two weeks.
Grr!! 
And breathe.