Hi Chris sorry to hear of your plight..
If its over 3 years old some Audi dealerships would recommend a belt change at service time even if the current mileage hasnt reached what it states in the manual for replacement.
Hopefully they will help you out if you have Full Audi service history and a belt change has never been recommended to you at service time.
Worse case senario if they wont help out and you cant spend 3k get engine rebiult elsewhere or look for a recon engine to swap over,or get one off Ebay and pay to get it fitted. Heres one going for cheap money-
AUDI A4 2.0 ENGINE CODE BWE /LOW MILES OUT OF 56 REG on eBay, also, Audi, Car Parts, Cars, Parts Vehicles (end time 16-Feb-08 20:54:24 GMT)