Rear axle does not spring in

Hello, so it's a 3.6 with level regulation. He's very hard on the rear axle. People have already asked me if I had a kangaroo in the trunk... I've been looking for a lot here in the forum. I've got the level-reg. (b) the When I press this winch bar forward with the engine running, the rear pumps up a few cm, I let go, it sinks cleanly. Think that everything is closed and all the lines are clear... if the dampers were over, he should actually become softer, because he only "absorbs" over the springs. He's not resonating. He's just hard on the back, koni yellow is nothing against it. Anyone's not idea? And where do I get these special dampers? Just at audi? Oh, yeah, I bought it like that, so I don't know if it happened suddenly or slowly.
Thank you