Originally Posted by Bcube
The part numbers are on your copy of the Service Order you signed.
And old parts that need to be held/audited/returned to manufacturer by the dealership that are warranty and or recall related will not be given to the customer.
I had not thought about them being returned to the manufacturer - you are correct with that. I think the OP is concerned that they just "made up" the work without actually doing it. But BMW would not reimburse them for the work if they did not get the core back I would suppose ...