when i replaced the pads on my 300 tdi the pistons were realy tight to wind in on one side had to put the caliper in a vice now the car pulls towards the dodgy caliper under breaking. would new pistons and seals and a good clean out of the caliper sort the problem

Corrosion on the pistons that is lifting the chrome plating so they are sticking
the permanent fix is to replace the piston or fit a peplacement caliper s/h or new.