I have 3 good reasons why:
1. First they replaced the wiring harness and said the problems fixed.
2. Then in my second visit they said it was the injectors; they replaced and said your problems fixed
3. In my third visit they said the throttle body is the culprit and for sure if it is replaced my problem will be fixed.

Understand that I don't know the difference between MB, MB USA, or a dealer. I am looking at it from a customers standpoint and from the the whole experience. One mis-diagnosis, ok. Two and I'm suspect. Three and I'm floored that couldn't figure it out after having the car for weeks.