Originally Posted by PropellerHead

I think you'll find that BMW does not sell the lens only. As part of your request, I would ask that the BMW parts/service adviser make a note that there exists no part number for just the lens on '04 and up E53's.

The folks at Costco are not without precedence in asking for lenses only. The parts are available for E39's and some early E53's. Costco seems simply unaware of this change for >'04 E53s. I wouldn't expect too much of a battle with Costco if you have the correct information from your dealer. They've already admitted to the error and said they'd address it. The repair is just different/more than they expect.