My mate booked an appointment and got the quack to fill it in there and then free.
All you can do is keep hassling them, I'm sure they'd do it to shut you up if you were tactile enough, ask why its taken so long? Book an appontment and ask the gp direct?
Its hard because there is no obligation for gps to sign the form, and they can charge what they want, there has been reports of this before.
Gp's now run as a buisness not a service (my own gp told me this years ago),