Had mine replaced for free 6 months after ownership of the new car. Bad design on BMW's part, but it's not covered under warranty. Most of the plastic hinges fell apart.
Some of it is my fault - I have placed heavy cooler on the lower tailgate many times, and also put my own weight (knees) a few times doing something back there. The hinges should probably not be plastic, or at least not as thin.

Dealer replaced free of charge (nice).