I stay away from BMW at all cost. The only item that I will ever have them work on is alignment because they are the only place that can do it correctly.
I didn't look at your area but I would get on the phone and call every shop that can and will work on a BMW. Ask what their shop rate is, ask if they check your car and find the problem that the diagnostic charge is waved.
Many shops will work with you on this, you have to be firm in your request and get everything in writing.
I have two shops that I trust here, one will let me shop for parts and that is a plus because everyone marks stuff up or charges a higher shop per hour fee. Eventually you will find the best shop for your needs.
The shop I also like the best is great at the hourly rate, does quality work but is slow, I add two days to his quotes right off the bat.
Hope this helps again the dealer would be my last resort.
97 740i e38 - SOLD
02 745i e65
03 Montero Limited