I would hope the brake light switch not working would
not keep the car from running but sometimes I underestimate the genius of the German engineering design team at MB
.
I can't say exactly for your model but on the late model S classes around here they have to go to the dealer to get a new gear shift module because it is part of the drive authorization (security) system. I think it retails for around $700 in that application. It is actually pretty easy to change out on the S class cars.