Unfortunately my local BMW dealer is a apprentice mechanic training center. They seem to break as many things as they fix. When things have gone wrong it took 4 days to get the car back.
The biggest mistake I found when getting work done the by the dealer is not insisting on a courtesy car. If you aren't using one of their cars your work goes to bottom priority and probably the least experienced mechanic too. I stopped using the dealer and get both my cars serviced by a BMW specialist mechanic.
For me its not about saving money, its about having an experienced professional perform quality work, rather than the young guys doing their apprenticeship at the dealer.