Dealers should certainly be aware to the possibility of work having 'side effects'. When enquiring how long the DAB retrofit takes the dealer advised me that it's 2hrs but that they keep the car for the whole day because (even following BMW approved fitting procedures), they also fully retest iDrive and the car's features to make sure everything still works as it should. They even gave examples, e.g. they test that the electric seat memory still works as it should.
2012 F30 328i Lux', 8SAT, Melbourne Red
On order:F30 340i M Sport, Estoril Blue/Oyster