Since your E55 is fairly new, I suggest you go back to MB, and let them solve the problems. And at the mean time, see if there are any consumer protect association(or anything like that which protect a consumer's right), and give them a call/letter to make sure MB takes the problems seriously.
I hate to say that, but I know some MB dealers in Canada has well-known reputation of ignoring their customers especially if..
1. The customer is or looks young(like myself. I have been ignored for an hour when I took my car in for service. I was basically sit there, and doing nothing, while my car is still outside, waiting to be serviced). Who says a 20-year-old can't have a Mercedes??
2. If there's no pressure on the MB dealers and/or MB HQ in USA/Canada, they would simply ignore your problems, and leave it(or them)as is.
So, go look around, there should be plenty of place you can go, give them a complaint letter/call, and I am sure your problem will be solve shortly.....