Help: North Eastern US Audi Service Rep didn't fix it...

At this point, I'm exasperated. The car originally went in for starting trouble, was diagnosed as being a fuel pump issue, and the pump was replaced. Went to pick up the car (this is about 6 weeks ago) and it ran rough, ABS light was on, and then shut down. Shop narrowed it down to a bad ECU, which they replaced, as they said the only way it could have been burnt was if one of their guys crossed cables while jumping the car. After that, the car would run perfectly for 15 minutes, then shut down. They were unable to locate the problem, so they took it to the local dealership (calling in a favor since they buy many part from them). The dealer techs couldn't locate the problem, at least not until the US service rep for the Northeast came in and found the problem to be the temp sender circuit. Still didn't solve the problem; my bro went to pick up the car today and it shut down on him after a couple minutes.


What recourse do I have here if someone as high up as the area service rep for the North Eastern US can't solve the problem, if I have any recourse at all, that is? From what I've read elsewhere on the site, such a rep is supposed to be trained by Audi in Germany, yes? Any advice is highly appreciated.