dont settle for immitation Benz products. most glass places will get the OME replacement parts if you insist on it.
I was also offered the cheaper replacement and turned it down.
if it doesnt work right inform your insurance company to go after the window installer..they will have to fix it or the insurance company wont pay them.
take it back and get the real parts.
1982 380 SEC
make sure they really know how to replace mercedes parts the company I used didnt and tried to do a cheap job. Called the insurance company and they made them do it right with in 48 hours.