Much of the loss of compression problems are due to the rings sticking in their grooves. This has been a problem on many late model cars due to the oil change intervals.
Unless you have crashed some valves, ran it hot, or ran it out of oil, I would look into that. We have cleaned and decarbonized a number of late model engines and restored the compression. If the problem is wear its one thing but if the rings are stuck like so many are you may have another alternative.
Of course I presume this 2002 must have bunches of miles or MB would be taking care of it.
Bosch Master, ASE Master, L1
33 years MB technician