I live in Blackheath, S.E London, and my nearest main dealer is at the top of my road. I acquired my X3 last year and took it there for a CCV failure. £750 later after they initially miss diagnosed the fault, first claiming my ignition coils were wrecked, then saying they had solved the problem but had then discovered the Cyclone Valve was amiss. Technical jargon for the Oil Seperator (CCV, so I understand from various websites).
I got the car back and it wouldn't start that quickly, having a lack of confidence in their competence, I decided to look elsewhere. I was recommended by a mate at work that I take it to DandT Wise in Bexleyheath, Kent. Their chief mechanic diagnosed the issue within 15 minutes and told me the Camshaft Sensor had been left unplugged, probably after rectifying the CCV. One would think they would have checked to see the car was fixed properly after doing the work, useless!
When I went to hand over my card to settle up, Danny, the owner, waved his hand and said "No charge. By the way, it's long overdue a service!'
The car is now booked in and thankfully that is the last time I will be sending my car to a dealership again. I can't recommend them enough.