Happened me recently, tv was only 4 months old when it happened, it was an LG tv. Contacted the retailer, they told me to contact LG, LG told me to contact their agent in Ireland, thus ensued 6 weeks of faffing about and LG not coming back to me, eventually ending with the tv being collected for repair and 2 weeks later no one could tell me when it would actually be repaired. I ended up in the retailers store (you cant phone them of course!!), and complained long, loud, threatened them with the joe duffy show, the small claims court etc...
Next day i was given a brand new tv - in a brand of my choice - i did not choose LG again. I googled the problem and its a pretty common fault in the type of tv I had. My biggest issue was the sheer lack of info coming from LG, no one could tell me when it would be repaired, if it would be repaired, what the delay was etc......