I fitted the correct VW brake light this afternoon and it was so simple because it fitted properly! The ebay one which claimed to be VAG was a waste of money! Poorly made, springs not held in place properly, but the biggest problem is that the unit was flat where the tailgate has a slight curve, so I was trying to bend it to fit. The VW one had the right curvature. I am now a practiced hand at removing and replacing the interior trim around the window, but I did mark the blanking covers getting the blind hook off!
Buying the correct part in the first place would have saved a lot of time and frustration!