Dubstter

I'm seeking some advice on an issue I've had with my dealer. About a year ago, I went in to do the timing belt change, per the service manual. When the dealer did this, they neglected to replace the stretch bolts (one time use bolts), even though they are a required part of the Audi Service guidelines. They instead, chose to reuse them.

Fast forward 8 months. The bolts snapped during a drive and the engine started making an awful sound (a whine similar to a belt rubbing on something). Luckily I was able to make it back to the dealer without any catastrophic failure. The dealer ended up replacing the bolts free of charge after some persistence. My question is what else should I be worried about? Is there any long term damage that I need to be aware of in this situation?