Changing the tires (left to right to left) can solve the problem. If the car has run a fairly number of miles with the current tires and these are still in good condition and are not worn in a strange (one side only) way, it is probably no alignment problem.
Like Jim told it can also be caused by different tire pressures.
Any tire place with alignment equipment can do the alignment; they have got the necessary soft ware for Benzes. You don't have to go to a mercedes shop.
with a minor 600+k