Recently purchased a 2015 A4 Allroad. Once it got cold out, I experienced the same issues. Squeak from the dash when driving over bumps. It’s origin was right around the bottom left corner of the nav screen trim and was made worse when the heater was on high. It would stop if I applied pressure but start up as soon as pressure was removed. It drove me INSANE. Decided to take apart the dash trim (a good view of how to here )
once I popped the bottom of the trim, right under the screen I could see clearly that the foam adhesive used to insulate the contact point around the clip area was worn through causing the metal clip to rub on the plastic anchor. The solve was applying a piece of gaffers tape(or anything adhesive that can create a barrier between the clip and anchor) to the anchor area where the foam was worn. Popped the trim back and it was good as new.