I took a BMW into Roberts Automotive for a passenger airbag light that would not go out. He ran a diagnostic test and I was told that the instrument cluster needed to be replaced at over $1000. He replaced the device and the problem came back the 3rd time I started the car. I took it back and he ran another diagnostic test and told me that it appeared to be the "Clock Spring" in the steering column. This would cost over $400 dollars to fix and I told him that he did not fix the problem the first time and I was not going to pay another $400 for him to keep guessing. He then proceeded to charge me $47.50 for the second diagnostic test.
I took the car to the BMW dealer and told him what was replaced and what Roberts had determined was the cause of the current problem. He looked at me and smiled saying that in 20 years of working on BMW cars, he has never seen the instrument cluster cause that problem or a clock spring break in a BMW steering column but they would be happy to run a diagnostic test and fix the problem. I was called within 2 hours after leaving the car for service and they told me that it was fixed. The BMW service manager asked me if the car had been taken to a detail shop recently and I told them yes. The service manager told me that a connector under the passenger seat had come loose and they reconnected and cleared the fault. They charged me $108 and I have been driving the car over 6 weeks and the problem has not come back. Do yourself a favor and take the car to a dealer, it will save you money in the long term and the dealer will guarantee their work.