You should bring the car to the dealer and ask for participation in the cost of the repair.
If your car has less than 120 k,they will probably assist in the cost of the repair if not the whoole thing.
Tell them you will deal with them,such as you will do your major service or some other needed repairs that they can make some money on if they will goodwill the harness.
YOU DID'NT HEAR ANY OF THIS FROM ME.
PS....A junkyard harness will be the same as yours.
Mercedes Benz Master Tech
ASE Master Technician
Owner of "Behind the Star Inc."