use a large G clamp to put the front pistons back in when changing pads, if its hard to push back, its fecked and they will jamb on when you brake with the new pads. (mine did that - usually the passenger side cos the guide pin bores get full of sh!t from puddles etc)
The guide pins have little gaiters which must be fitted properly and have no holes. A new set of guide pins from VAG are about £12 with rubber gaiters. If you dont fit new gaiters the brakes will last less than 6 months and seize again.
The rear pistons need a VAG tool as they screw in and out using microthreads cut into the outside of the piston and CANNOT be put back using clamps. They are a b!tch to do and the carriers are usually seized solid. I got kwik-sh!t to do the rears cos they are a bastard to change. It took me 7 hours to change the front discs with all the tools and a garage to use. I'm an engineer and I do similar stuff on machinery every day and it was still a thingy of a job.
Good luck mate
just be persistent and dont give up.
You need a 15mm open ended spanner, a 13mm socket and wrench, a G-clamp, and if you have to change the carriers - a 17mm BIG spanner or hefty socket wrench to remove the carrier bolts (and a 1/2 Lb hammer to break the lock on them by hitting the spanner end in the loosening direction). Soak them wi wd40 and leave for 30 mins to soften the rust. The discs are held on at the front by an M5 countersunk machine screw with a philips head. A 4mm drill can be used to drill through the screw and pick the remains out of the hole. As long as you put a screw back that bites then the wheel bolts will hold the disc on when the wheels are re-fitted. The screw just keeps the disc still so you can get the bolts back in.
