Gear ratchet 3.3 TDI Quattro

Hello again. I've already described my problem with the rear gearbox when driving backwards. Maybe someone knows this or something like that! Would not like to "surprise" me in the workshop and therefore I am looking for information in advance.
So: I have now observed that this problem does not occur with cold gear oil. With warm transmission, reverse rolling is only possible in the stationary gas. Under load or when giving gas, a ratter on the rear axle is heard as if the wheels are spinning, with simultaneous drive limitation. I really spared the car, even when parking I always pulled the handbrake first and then first mode "N" and then "P" to avoid jamming the gearbox.
Since it is nevertheless obviously a mechanical defect I am already a little angry at a km-stand of 99.500!! Isn't it normal??? Or does anyone know if it could come from an electronic error? But no one could be read! Guarantee or something like that will certainly not exist anymore??? Well, I have an appointment with Audi on Thursday, so I'll tell you what they said. Lg Ronny