The "main office" didn't acknowledge anything, they figured out how to fix it. Once the repair was verified the dealers were sent work instructions from the factory. Please re-read my post.

The reason it can take some time to sort out issues like this is simple. MB can't drop everything when one guy complains of an engine knock. Once they've received enough complaints though, they'll dedicate the necessary resources and do what's necessary to solve the problem. The one thing that most PP members won't be thrilled about is that they normally won't re-visit issues like these after the factory warranty has expired. They've been doing it this way for many years, longer than I've been aboard. Same goes for voluntary recall and service campaigns.