Caliper on front brakes rattle on 2008 A6 (C6) Avant S-line

[Alfie6]

Hi - I have recent acquired a 2008 A6 (C6)avant sline and I am experiencing rattle from the front brakes driving over rough road surfaces. I note the car has recently had new discs and pads and only 10% worn. I have renewed the caliper springs on both sides and this has largely improved the problem but annoyingly there still some rattle from both sides. Being a sline with harder suspension is this a common problem on these cars on our bad roads. Further my local  garage has inspected the suspension and can only find that anti-roll bushes may required to be replaced in the distance future, and could only be an advisory on the MOT, but offer no more advice. Anybody had the same problem and solved it?