If the screen has any heads up display or sign reading camera, they fit a pukka BMW screen as it has to be properly calibrated and they don't have the equipment. They have to send it to a main dealer who will not touch a non BMW screen of course.
That was Auto Windscreens late 2017 - The screen was fitted to my 335 (on the drive) without a hiccup and I was totally happy with the result and especially so after reading some of the horror stories on here. Six years down the line, I'm still happy!