The lights do not come on when I push the button on the drivers side, but the lights come on and the heater works on the passenger side. Is this likely a bad switch? Are the drivers side and passenger side on separate fuses? any advice?

 

It could be a fuse, but it could also be a broken wire or defective heating pad in the seat. Use a multi meter to check continuity in the seat wiring..Disconnect the harness that comes up from the floor and put one of the leads from the multi meter on each of the terminals in the seat connector. If you don’t have continuity the problem is likely to be in the seat.

 

it appears to be a bad heating element. who makes a good replacement?

 

Check out this thread:Seat heater replacement

I had my seat heater replaced with a Dorman model 628-040 Universal. The seats in a C55 are significantly different from those in a C230 and I'm not sure the same model will work in your car. My problem was in the seat bottom, but it is possible that your issue could be in either the seat bottom or the seat back. I guess it is also possble that both pads could be defective or that it is a broken wire.