I would attempt to find an accredited Euro Shop experienced in Mercedes and have them run a scan. We have a good one here in Austin that I would trust long before any Chrysler Stealership. It cost me 48 bucks to run a complete scan on "Rosey" and saved God knows how much when it turned out to be a bad wheel speed sensor that I was able to replace myself.
Good Luck !

Just my Dos Centavos