Can you obtain another claim form - they may have lost the original and if you go in with it as an appointment then wait whilst it is is signed.
You pay for your vets and you should expect a reasonable service from them. On a couple of occassions at my old vets (now moved) I had cause to query their bills, having been charged twice for a couple of things and for an overnight stay after they had told me to collect my girl. Perhaps you could mention copying in all paperwork and dates and times of conversations to the RCVS.
Good luck, let us know what happens. Also, have you spoken to your insurance company, perhaps they can put pressure on them.