Do A3s/S3s suffer from the brakes getting wet or covered in muck/salt during high speed winter driving in wet weather???
Very occasionally on long wet motorway journeys where I haven't needed to brake for say 30mins or so, when I go to brake there is practically no response initially. Which can be scary. I have to really stomp on the brakes to stop and then thereafter they work fine again. It seems to be a winter phenomenon - I last noticed it stopping for a peage in France last February and then it happened again this year on the autobahn in Germany two weeks ago. It was wet (surface spray) and salty (was snowy) and I had to brake hard at approx 110mph and absolutely nothing happened at first. The brakes did eventually bite but I absolutely bricked myself.
The brakes themselves are fine - the car had a brake fluid service last month - so not sure what's causing it? Never had this problem with any previous car.