'92 E320 Problem with signal & Hazard light
 

I'm having problems with my 1992 E320. For some reason, the signal lights doesn't work. Also all options on the center dash doesn't work either. ie: door unlock button, lowering of head rest button, hazard light button, and also the signal lights. I have checked the fuses and they are all fine. Took it back to wherethe used car dealer where Ipurchased it and they did a check and could not determine what the problem was. They suggested that I take it to a Mercedes dealership for testing and repair. I'm sure it is going to be a lot to get this fix. Has anyone experienced similiar problems, if so, what was the deal?
Thanks,
Seyah