Sorry to see you are in the same boat as anybody else dealing with a dealer! We just yesterday got our C230 back, 2 months after it was taken in to MB of Laguna Niguel for the slipping transmission (after they rebuilt it and/or replaced parts twice by 21000 miles!). YUP, OVER 2 MONTHS WITH NO CAR!!! Never any response to certified mail letters to the General Manager, no response to faxes or emails, and it took 1 month before the MB area rep got around to phoning me (and then he complained about my having been upset in my latest letter that it had taken him a month to respond!) MBUSA took 2 weeks to respond, with a form letter saying that the area rep was in charge and his decision to not do anything until the trans failed was final ("no matter how many of your friends, coworkers, car pool riders document the slipping, it aint slipping if there are no codes and we don't see it slip! But we will consider goodwill repairs within a reasonable time!").
Finally the only leverage I had was to cancel the extended warranty on the car through my credit card company to reclaim some funds to apply towards the transmission in case they don't cover it when it fails. After the card company contacted them, they 'offered' to refund the warranty.
When I took delivery of the car, the deck lid looked like it had been keyed over a 1" x 5" area, and I had to wait while they tried to polish most of it out of the finish.
This is not how a manufacturer stays on top (if that is where they are!?!)