I've seen a lot of people talk about creaking windows seals on this forum resulting in the dealer applying a silicone gel to temporarily fix.
Thought I'd share my experience in case it helps anyone here. First time around, my dealer applied silicone to the seals but six months later, the creaks were back. I took it back to the dealer but this time I asked them to check the window alignment. What they found was that the window control unit was faulty (dealer mentioned this is very common in the A3/S3). Since replacing the unit, I've not had any creaks. Much better