I had this exact problem. The Active Body Control (ABC) "Visit Workshop" alert on your dash could mean a number of things as the ABC controls a lot i.e., suspension, lowering and raising car, and driveability. It could also be a leak in your power steering. Check under your car, after it has sit for awhile, and see if it has any leaks. If not then it is most likely your ABC compressor or your struts or suspension in general. The ABC comprsessor runs the air through your suspension which lowers and raises your car, it also keeps your car in a steady line when driving i.e., the ABC button that you push to tighten up your steering and your suspension, or the button to raise and lower your Mercedes by 3" or 6". Bring it in to Mercedes and make sure that it is either under warranty or you have an after market warranty that will cover this. Mine just went on me, because of a failer that a shop, to remain nameless, did to me. They added power steering fluid to my ABC channel and it ran all the way through my system. Mercedes had to flush the entire system and replace the ABC pump/compressor. The job cost me $3750, mostly labor. There is sometimes a quick fix and the part is a front strut air leak patch. You could have an air leak in your front struts, if so then this won't be as bad, the part was $200 for both struts. If it is not that and it is your rear struts, then that will be expensive. So go visit the workshop now (Mercedes only) as other shops do not know how to work on our Mercedes, I am not a dealer or repair shop, just a fellow Mercedes owner and have learned the lesson of trying to save money at another shop. Mercedes cars require Merdes parts. Bring it in and with this information, tell them what you have learned. Hope this helped.