Well you would go to a general practioner before he sends you to the brain surgenNot to be a snob but you don't go to a general practioner for brain surgery. If you chose not to go to the dealer for service, find someone who is trained to work on German cars. Look for Bosch trained technicians who know the systems on German cars.
So why not come here and get advice first rather than going straight to a dealer and getting charged an extortionate fee for something you can do yourself !
Thanks marti5 your help is much appreciated