Unfortunately miscarriage isn't a high priority - probably because things will happen naturally themselves if left alone. Mind you - if you developed an infection or had complications, they would probably put you up the list a little.
I remember the feeling of being bumped one day, and then being sooooo stressed the next day. I was even told to see how many police cars were outside the emergency ward when I arrived as that would determine whether there were lots of emergency surgeries on or not. Luckily I got into theatre about 9-10am or so?

Can I suggest going in and crying, wailing, doing whatever you have to to suggest you just aren't coping with it? Psychologically they might do something for you then.
I am really sorry, at least your GP is on your side.