About the rear wheel bearings, we're an O.E.M. of plastic production machinery. If I had a part break on one of our machines and the customer did not come back to us for a replacement and just bought one locally, I would not offer them warranty on the part.
In my opinion, the dealer has no choice but to go through MMC for the parts for a warranty claim.
If it were out of warranty, I would cross reference and buy locally and be back on the road.
It sounds like they got the M3W back on the road quickly, even with the part coming from MMC.
Good luck with the Check Engine light.
