See if you can find a GOOD mobile mechanic. I have one who has saved me a lot of money over the years. The person you're looking for does NOT come to your house with a little tool bag in the trunk of his car, and he is not 24 years old. Instead, he comes with a van full of tools and is 35 years or older.

Though my guy doesn't know everything about Mercedes since he's a generalist, he can figure a lot of stuff out and when he doesn't know something he tells you so. He knows his limits of what he can and can't fix.

Good luck.