Grundig TV LED Screen Failures and Warranty Denials

I bought a Grundig TV, but the LED screen broke after a year. I called the service center and asked for a new one, but they said they could only fix it. They said the issue didn't matter, so I reluctantly agreed. But a year has gone by, and I still have the same problem. The LED screen has broken again, but now they say my warranty is over and I'll have to pay to fix it. I told them I wasn't happy and asked for a replacement, saying I didn't want this broken product. They say that since the warranty doesn't cover it, they can't give a replacement. But even though the problem was covered by the warranty, they didn't replace the item. I want the right people to do a thorough investigation into this. I don't want this thing that keeps breaking; I want something that works.