I would suggest that dealerships are getting a bit funny about giving part numbers out now, probably because people use them to get part numbers and then buy used parts online.
I had a recent experience where I wanted a part, it was not in stock and had a considerable back order and still they would not give me the part number or allow me to order the part even on back order which was just a dick move all round… ‘no you can’t order the part and no I won’t give you the part numbers so you can at least try and find it else where’