Have you tried a factory reset ? Disconnect everything connected, too.
If the problem persists, I would contact the retailer. Where did you buy it ? It's safe to presume that a TV should last a lot longer than that, regardless of the warranty.
You do have
certain rights when you buy anything here in the UK, but claiming under these rights gets more difficult once you've owned something for more than 6 months, by the looks of it.