Around 70,000 I think. Check your warrenty book, it would have the answer in there or you can call the garage to find out.
Try to get it changed at the same time as you are having a service done, that way you can save on two hours labour!
Thanks. I don't have a warranty book because i don't have an Audi yet. I'm looking to buy one and want to check that the guy isn't telling me fibs! I might phone Audi for a figure...