Replaced this one... though it is still working.
whoa. It looks almost worse than the one I replaced.
Originally I thought the rusty appearance on mine was due to the leaky sunroof, which the car had lived with the first 10 years of its life, but now I think it is more likely to be caused by the current. Probably the connectors are designed (under-dimensioned) to become "a little" hot when used, - which accelerates the corrosion.
Apart from buying a fire extinguisher, I think all Murena owners should take a look at this switch and its connectors. Same goes for some of the connectors on the fuse board, which carry a lot of amps.
/Lennart