OK, E90Post is littered with horror stories of how this and that dealer did something awful.
Here is one on the brighter side. Took my 335 in for an oil change, and a brake squeak check. Got a 328 loaner, went to work. Needed to make a call to my wife, couldn't find my iphone, figured I left it in my car. I am pretty spacey at the moment, just got back from a trip to Finland and I am seriously jet-lagged. Too much fun staying up late, what with it being light out until after midnight there.
Decide to drive over to dealer and give them the spark plugs that I had changed a month or so ago. Get there and ask about my phone. Turns out I left my phone and wallet on top of my car. Tech notices a thump when he takes it for a test drive, sees something fly off. Stops car, retrieves phone and wallet and everything that was in it, including a few U.S. Grants.
So I get my phone and wallet back. And the SA decides that because I'm within a month or so of scheduled oil change that it is free -- I change my oil every 7500 miles, so I usually have to pay for every other one, but not this time.
This is one of the primary reasons why I will always drive a BMW as long as I live in Columbia, MO. Some of the best techs in the USA, and the best Service Advisor. My car works perfectly, including the suspension install a year later. Very, very happy customer.