Compatable Key Fob - 8LO837231? A6 2.8(97)

I have an old style rigid - 2 button key Fob (8LO837231) - I have searched and searched to locate the correct compatable part number or transmitter so i can buy a new flip key. I have found numerious information on re-programming cental locking and coding immo.

I have contacted Audi and been given a price (£148) but no comapatable part numbers given.

PLEASE HELP