Dead Head Unit
I'm surprised this shop didn't have the correct tool. These removal keys are not used only on Mercedes afterall; they're also uses on Audi, VW, Porsche, maybe others. Maybe I'm being too critical, I don't know.
Anyway, there should be shops around who can help you. You can also find the tools on ebay, most around $8-$10.
The fuse is a 10A...good luck.



