I had the same problem in my w201, the driver seat had two of the four springs on the left broken!

first I tried to fix the problem, but I realized that the car was extremely uncomfortable for a longer drive, my back and my left leg would start to hurt really bad.

I switched the driver seat with the passanger seat, just the bottom parts, and so far so good, I still had to adjust it a bit to get as much comfort out of it as possible, and I have to say that this area in an MB could use some improvment.

Nevertheless, I don't notice it anymore and I'm able to drive the car without any problems.

xp