Hi Jo, this seems to be a common fault but unless your TV is still under guarantee, you may have problems getting anyone to accept responsibility and compensation.
I suspect your TV (prior to the panel failure) would randomly switch itself off?
I strongly suggest visiting the below forum and report your problem there as they are trying to co-ordinate a response and the more evidence they have, the stronger the case for successful remedial action will be.
http://www.avforums.com/forums/lcd-televisions/807012-sony-bravia-kdl-32d3000-purple-vertical-line-faulty-14.html
Best regards,
Martin, September 2009