Leave him alone! If the man has a cold arse, he wants it warming!!
Personally I'd trawl eBay for some good second hand ones from a similar year car in the same leather or fabric. Make sure they give you the dashboard switch and the wiring - then get a decent mechanic to fit it. That'll be a lot cheaper than getting Mercedes to fit new parts!
Failing that - after market options are the heated seat pads, or heated seat covers. Just go onto eBay and search up "heated seat pad"