You may want to view all posts on the "Good MB Shops" section, you will find one or two recommended shops in your area (South Orange County). If your current tech has not solved the problem, he may or maynot know your car well enough.
Also, try running a search on past topics with the "search" tool in the upper right area of this page. Use something like "code AND read" in the search words area and you should find some info on reading the codes your self.
Keep us updated, with more detailed info your problem should be fixed soon.