Sorry about the misunderstanding, but when I said "123 mirror," I meant the mirrors in the W123 cars such as my '84 300D. Your car must be a W201, and I do not know if the mirrors remained the same throughout the years and body style changes. Someone else will have to chime in on that.
The point is, have you tried removing the mirror by hand, in the manner I described? I know you may be fearful of breaking the mirror, but (again, if it's like mine) it should pull off one side at a time.
1995 E300 Diesel (Die Blau Frau)