I gave him a call, arranged to meet him and he removed my pump, replaced the motor with one with a thicker graphite part, re-installed the pump and tested it while I waited. It was quite amazing how chewed up my grapite impeller was. The reason for the thicker graphite part (9mm as opposed to 6mm) is to prevent a re-occurance. It seems to be a fairly common problem on 90s cars due to good old Audis cost cutting.
He charged me £160 which I feel is money well spent as I had got totally fed up with having to remind my family to lock the doors and repeatedly setting the alarm off. He has also given me a 12 month guarantee on the repair. For those who are further away he is happy to offer a postal service and can also supply parts to do a DIY repair.
Even better he was also a very pleasant and friendly guy and a fellow Audi owner. So far he has fixed about 170 pumps and keeps a stock of the common pumps and parts. He has Vagcom and if he has to swap the pump he can recode it to your keys. I am very happy to recommend him and suggest if you have a similar problem you give him a call and have a chat. Hi name is Fawad and his mobile number is 07876 542430.
Next job - Sort the air conditioning... not helped by a regas

Cheers,
David