LG 55 nano dark patches on screen - LED failure?

HI - Can anyone shed a light on this - had an independant quote for a new screen - £580 + labour and VAT - also asked LG for a quote but no reply yet!..... TV is 18 months old and become pretty much unwatchable..
Model Number  55NANAO866NA No 010MAKRCP709. TV Purchased Autumn 2020. TV Manufactured 10/2020 in Poland. Purchased from Currys. The TV has developed a dark patch running vertically in the centre of the screen. It covers approximately 1/5th of the picture - that is still visible but is very much darker. First the fault was intermittent but now it appears that the fault is permanent.