I too had this rear disc wear saga at 20k. I also had the stealers glib,"must have been standing etc ,etc" and since I use the car every day, that is a load of proverbial arse! The voice at the Seat customer services escaped strangulation due to the diameter of the GPO cable! So I paid up to the stealer.
Reading the threads I note there has been no direct answer for this
problem. Since the easing of my purse strings, I have become a bit of a Golf rear disc spotter
and the wear patterns I`ve seen are what I recognise as normal on a rear disc braked car. Since the
Ibiza digs into several VAG part bins, is the pressure arriving at the rear end sufficient,under NORMAL braking, to force the pads effectively onto the discs thus ensuring no build up of rust? So, is the master cylinder pressure split between front/ rear correct? Are the pads too hard? Any ideas chaps? The brakes on my wifes Octavia are the dogs!
Incidently, I also had both front springs break at 27k, two weeks apart, but Seat only change individual springs and not pairs!