Problem with my TV (Samsung UE55ES6800 55" ) any idea on fix?

[Spike2k1]

Hi all, I've had my to for about 4 years now and the past 6 months I've noticed these lines getting worse coming down the screen. I've tried various sources, cables etc so know it's not the connection and definitely on the screen itself.

It's a Samsung UE55ES6800, cost a fortune when we got it and really would like to keep it working but when it dies I'd probably just get a cheap 50" from Asda etc.

Any ideas on a fix / reason for the lines?

https://imgur.com/a/HOu9h

Thanks in advance.
(Hope this is relevant section to post it in)