Hi all, I need advice on a 2004 Audi A6 2.7T with a satellite radio issue.

I have had the car for a month and this seemed to start after I got the windows tinted. My xm is factory and it plays great, but then it will go out on the left side. Right side still plays fine. Tried the CD player and the FM stations and both sides work so something to do with the satellite radio. I don't know the wiring for this car as it is my first Audi. It does seem to happen when the back wheels go over a bump, like a speed bump. Sometimes, I can drive it without it happening. Seems like a loose connection because the volume will decrease then increase slightly.

Please help....I would like to know if its a loose connection or if something else could be the problem. The nearest Audi dealer is 2 hours away. Could the stereo shop that tinted my windows maybe know how to fix this?
Thanks,
Robin