Look for Bently Manual,sure they do A6 model as owdgit says straight forward job if you know what you are doing ,if you have change pads before then it will be straight forward ,just to remember that when pushing the piston back in they might screw back in rather than push (try first)Clean down caliper before putting in new pads in plenty cooper grease on the back of the pads ,check discs for wear before putting in new pads aswell as if they are nearly done you will be doing the same job again very soon and having to buy pads again and discs
Cheers