Hello Eric,
If the clips you are referring to are c-shaped with a little bulge at the back, then the part number would be: A180 993 05 25.
According to the EPC, the part number for the bulbs should be: N072 601 012 160.
I can however not confirm whether it is in fact 18W bulbs that Mercedes supplies these days as I have obtained mine from a local Osram stockist a few years ago.
Maybe others that have ordered from Mercedes can confirm this.