Well, i took my passenagr side rear wheel off last night and had a good old poke around and have found the cause of the problem!
The calliper carier had one of it's floating bolt things (excuse lack of proper terminoligy!) seized, rusted solid. and where that had seized that inside pad had worn away completely, all pad material gone and down to the more solid bit of the pad that the material sits on... which has worn a nice groove in the disc!
So, new rear pads and discs and a new calliper carier! Not too disapointed with that as funnily enough i had the exact same problem on my old car (A4 2.8Q Avant) so at least i know what i'm dealing with, and can sort it myself which is a Brucey Bonus!
Time to get on to the parts people
