Grinding on application of rear brake

[slider2616]

Bought new GSA 1200te in March, since day one on application of rear breake I experience a horrible grinding sound and vibration through the brake lever.
I have now taken the bike to the dealer to sort out on 3 occasions.
They have replaced the rear disc twice and on the last occasion replaced the final drive, none of which has solved the problem.
I have now been told this could be a "CHARACTERISTIC" of the model.

Has anyone else experience of this and could anyone give any advice as my BMW dealer has no idea how to solve this problem
Thanks

 

[(RIP) Tunneruk]

As ridiculous as it may sound I'd be checking the both the rear pads are in the right way round!