Hi I'm new to this sorry, my problem is I've just bought a a3 1.9tdie sports hatch 2008, within 20mins of driving it the car cuts out and will not start again, it's been in the garage 2week to no joy, it will start again with easy start and runs like there's no problem. They have changed the crank sensor, dpf delete and remove, cleaned all filters inc diesel tank, and also does not show any faults on diagnosis at all. Pls help?????