I would ask to see the service records, if you feel you are offending the dealer forget it, they have their money. They will bill MB for any and all warranty work, when that expires they will drop you like a hot potato. I would get a hold of the service manager, the zone rep, and send a letter to MBUSA from your attorney addressing the issues. I hope you never have to evoke your issues and the car is clean from here on. I would ask them to extend the five day return based on problems, any court will enforce that. If they dont, envoke the return policy right now!