so, I have a 2004 Allroad. Recently, my rear suspension has been acting up. I push the button to raise it, the front is fine but I can hear the back trying to raise it, but it never does. If I go over 55 mph the car drops to level 2 and the back end bounces like crazy. I stop, turn the car off , raise the suspension drive under 55 and it's fine. Any suggestions as to what it might be? Thank you