I have a much older MB (76 450) but I'd suggest taking it to a custom
muffler shop and seeing what they say. There may be an aftermarket
cat for you car, and while I'd normally never pitch non-MB parts,
the cat system really is just a garbage disposal.
But who knows, you may have other links to the system on newer cars
that make replacement more complicated.
still, $2200? for cats?