I had this problem on my XF, tried 6 or 7 plastic ones from the wreckers, and they ALL fell apart when I was installing them, so I went and bought a universal type STEEL one from Bursons and no more problem.

Gab

I lost my brake lights and it turned out to be a blown fuse.

The cause---There was a short in the plug that goes to Cruise control unit in the engine bay.

Bye Bye Cruise control.