Failed "clutch" on Fabia 1.4 TDI

I have a Fabia 1.4 TDI/80 first registered June 2009 but purchased by me with only delivery mileage on it in January 2010. It has only 20500 miles on the clock, 4000+ of those on 1 trip to Spain and only 1500 since being given a clean bill of health at MOT and service. I drove from northampton to MK and heading for MK centre couldn't change gear, I think I was going from 3rd to 4th or 5th.Drifted into a layby and with difficulty selected 1st and proceeded gingerly. Since then once the car becomes warm/hot gears can be difficult to select,being lumpy notchy and sometimes very difficult even when stopped. However on a short journey around the paper shop it drives as normal. I took it in to the dealer who said the clutch had gone and quoted me £619 for a replacement. I believe my case mirrows EcoAndy posted to this site on 27 Feb 2010. Any advice/ help out there would be appreciated especially from EcoAndy on how his problem was resolved.