I'm on the original set too at 30k miles. Someone on here some time back said the failure was due to the rear calipers not having been greased in all the right places so the pads would partially seize. Now I can't say that is true but my rear ns caliper was giving a light rubbing sound and had a bit of a score mark on it not present on the os which was quiet. I haven't noticed the noise for a while so haven't investigated further but if I were you I would get replacements done at a reliable independent who will do the job properly and see how you get on. A colleague at work had a crappy Peugeot which at 30k miles was having it's second set of replacement discs and pads, the dealer just said the parts were crap quality! Mind you, he was a bit odd and aggresive at times so I wouldn't have been surprised if his driving style matched...