Friend, I have a Jetta mk5 2007 Tiptronic from Mexico. I live in Brazil. A few months ago, in a hot tropical climate, when I stopped at a traffic light and was about to go back, the car would cut the engine, I had to restart it to continue. This was always repeated when it was hot and whenever I stopped in traffic or at a lighthouse, the strange thing is that the indicator light on the panel did not indicate anything! This bothered me a lot and I started my journey with different mechanics and even VW dealerships but nobody found out what it was. Until one day, I was recommended a mechanical specialist in a computerized system, I went to him and after the scanner went through, he concluded that he should reset (leave it as if it had left the factory), however, he had to remove the computerized board from the panel to do the reset. Conclusion, the problem is over. I don't know if this will help you, but it's just my suggestion after reading your story. I hope you can solve it, even if it's not because of my suggestion! Hugs!