What's wrong with the struts? Are they leaking? Concerning the "pressure block", there's more than one. Which one do thery want to replace, and why? The ABC system isn't that complicated. MB has published some very informative DTB's regarding the diagnosis and repair for some of the more common failures. Some of these solutions are quick and cheap.

Before you run off and spend big $$$ based on the dealers' diagnosis, you need to get some detailed information from the dealer. External leaks, fault codes, etc. Find out what you can and post the results.