I think there is a blank plastic cover which is the size of a switch, to cover this. For cars without certain options, (heated seats, etc?)
Maybe partsshop or the dealership? Or maybe an electronics place? This should be a cheap part.
1989 560SEL (172k)
1989 325IC (122K)
2004 Suzuki Volusia LE (3500 miles)
2005 Yamaha Road Star (20 K miles)