Audi Repair Questions? Ask a Mechanic for Answers ASAP
The simple answer is that it would be impossible to tell you! If the part has been modified then potentially it could last longer than that. All depends on usage and the type of driving etc. It isn't just Audi that suffer from this problem. We have had some issues with Nissans too.
You could contact Audi Customer Services and tell them you don't feel that this should have happened after only 65000 miles. You may find that in the interests of Customer Satisfaction that they may look at paying some of the cost you have incurred.