Originally Posted by THE TECH
That's not how it works. Only when they figure out the issue are you presented with a bill. They can't blackmail you into putting the car to stock before they work on it. If they work on the car and find the your aftermarket parts are to blame, then and only then, are you responsible for the bill.
Sounds like finding another more reputable dealer is in order.
They say the replaced the ECU (DME i think called) and some other modules (Spent ofer $3k) in parts and there are still problems... Now some guy from BMW is going to evaluate this as they can no longer justify the costs they put in. BMW seems to not like that they spent so much time/parts on it.
They seem to investigate.
I do know that my Smart Top Module and my Alarm Module as well as the Rear Camera Module all talk to the Can Bus somehow... But i can not imagine that they are to blame as the same stuff was installed on my 335i last year and there where never issues like that with it.