Please guys, this (front brake squeal) issue is not difficult to resolve: you just need to remove the brake pads, apply Copperslip, and refit.
Your local garage could do it for you; it doesn't have to be an Audi garage. You can do it. I have done it, successfully: 45-minutes of effort did both sides.
The most difficult issue on my car was the removal of the pads from the caliper - which is most probably the cause of the squeal/vibration anyway - as all four pads on my car were fast in the caliper, and had to be gently persuaded out.
However, if you do have front brake squeal, and you don't like it, then do something about it, please! The RS3 is far too good a piece of machinery to be bothered by something so easily rectified!