I have bought parts from the nearest Mercedes dealer to me (about an hour away)
I always use the Mercedes part number as they don't seem to have a clue there.
I don't know what the guy would do if he actually had to look up a part. He is super glad when he just has to plug a number into his computer.
This is why I am very appreciative of fellow members who include the Mercedes parts numbers in their fixes so I can get them easily.
No one has asked what car it was for and I sure did not volunteer it.
Jim