Good afternoon my name is ***** ***** I will assist with your query today.
To start with where are the coloured lines showing on the screen, and are they visible regardless of what source you set the TV it eg HDMI1, when you bring up an on screen menu and when you watch terrestrial TV?
Unfortunately this is a hardware fault on the T-CON board, which will need replacing.
I suggest you look to get this done at a local service centre, the part is around £70.
You can locate you nearest service centre by going to the link here.
Please let me know if I can be of any further assistance.