Suspicion of a defective articulated disc (hardy disk) F12 650i, question of service costs

Hello, ride for quite some time a 650i LCI f12. Unfortunately only problems. The first defect occurred at approx. 10,000km It was performed once repair kit inlay nut. The second defect then occurred at 12,000km. Very loud scratching in the high sound loudspeaker Bang&Olufsen High End The third defect then occurred at 20,000km. Aktor HSR had a defect (back axle steering) Now the car comes back into the workshop at 24,000km suspicion on joint disc (see video below.) Depending on the speed, you can hear a change in the sound. There is already a PuMA measure 35464351, unfortunately I don’t know what the meaning is! Now my question is what this may be about is the defect and if it might be something else! Another question about the Great Service: According to my dealer, it should cost about 2,000euro! I fell on my ass when I heard that The X6 or the 4s both cost no more than 500-700Euro! Is the price ok?