Thanks dx, appreciate it. I'll get on it

Hello New to the forums, any help would be appreciated. I bought a 37 inch Samnsung LCD tv in June 2008 and bought the extended warranty with it. After about 6 months of having the TV, the picture started blacking out, leaving sound but no picture, after turning the TV off and back on again, the picture would reappear and that would be the end of it. Recently the problem has got worse, at random, the picture will black out leaving only the sound. Turning the TV off and back on no longer helps, if I do this the picture comes back for a few seconds but then goes black again. Anyway *waffle over* I sent my TV in for repair 3 weeks ago, I had the TV returned to me within a few days enclosed was areceipt stating that no faults were found with the TV!!! At first all seemed to be well, but after a few hours of use, the problem is back/still there. Is there anyway I can get them to replace the TV, due to the fact that they have already had it in for repair, but not fixed it. Hope I havent waffled on too much, any help appreciated. Cheers:)