Off Center Steering Wheel (even after 4 wheel alignment)

Guess I’ll agree with you at this point; they’re completely incompetent. It sounds like all they did was screw the right side out some which in turn should rotate the steering wheel a bit in a clockwise manner. In this case, maybe a half round too much…
Of course, that leads into the possibility that someone just cranked the tie rod around a bit to line the wheel up (and apparently a bad guess) and the toe may be off now. Maybe it was off before and the situation is now exacerbated by the latest go-around.

It may be time to send the car to another alignment shop. Hold onto any printouts you receive and pay special attention to camber and toe specs. If the second shop finds a problem with what has been done then a firmly polite letter to the dealer asking for a refund might be in order. After that a more firmly worded letter to corporate Benz would be on the to-do list.
Those letters may accomplish nothing but it’s better to speak up on some issues rather than allow them to remain dormant. Enough complaints may create a change. Maybe…

Not only did they mess up centering you steering wheel, it sounds like they may have messed up your new alignment. It sounds like someone is following written instructions they don’t understand.