Hisense TV terrible

I purchased a Hisense 58" Smart TV a few years ago and last year, the screen went black and I called in as it was under warranty. Some one came and collected and repaired it and returned it and it worked fine for a few months. Now I see a fine vertical line running from the top to the bottom of the screen suddenly appeared. How does something like this happen after it was repaired so recently. I have only Hisense TV's all my life and have 2 at a the moment. I've never owned another brand of TV. My first one lasted me 15 years but based on this experience, I am considering never to buy a Hisense brand appliance again unless something is done to assist me and have this rectified,