I replaced all four of mine about 18 months ago.
Audi actually agreed to only charge me 60% of total price as they agreed that there was an obvious defect in design and manufacture. Worth a bash!
This, on a car that was 3 years outside of the standard warranty...
The fixing screws on the hinge end is a nightmare. I gave up trying to drill mine out and simply ground them down. The strips are very securely fixed despite not being screwed in.
Best of luck!
Cheers,
A.