Ethan brings up a good point about the battery. While you are in the area just ensure the cable connections are tight. Also check the ground cable connection to the frame/body and ensure it is clean (free of paint) and tight. Your battery is "out of sight" therefore it is "out of mind!"
The majority of technicians at dealerships will strive to duplicate a customerís complaint within the 20 minutes they may, or may not spend on it.
With MB's lack of favorable reports from JD Powers you can be assured that at some point the service area could witness some serious brooming to correct it.