^^^Unfortunately sometimes that is the case with insurance "sponsored" repairs.Insurance company refuses to pay for a OEM window,glass company installs OE.It doesnt work,insurance company says go with the more expensive glass.It doesnt work too,finally OEM glass is installed and insurance company pays more than if they did it right the first time.
Good,experienced installer will do a great and clean job without following BMW or Mercedes procedures.The problem with any company is to get lucky with your installer.