I did take it to mercedes and the did a diagnostic , l was hoping it was just something simple but they say it's the seat pad mind you it's more money for them to say that but what they are asking for on a old car is crazy
BMW F11 Touring + Porsche 911 Carrera S + Toyota Alphard Camper
Mercedes will put it on Star and will say the pad has failed, but I would check the wires, they fail all the time and 30 mins of your time is all it will cost you.
Thank you guys I'm going to check the connections again, although the diagram on the link didn't work I'm going to try call some in dependant garages see what prices they quote as £850 for a repair on a old car is a bit much