OnePlus India — Oneplus 8

My oneplus 8 device started showing green lines and then whole screen turned green and it happened after updating my phone one month later. It's an on going on issue with mant one plus phone. They said one plus 8 doesn't have this while they are plenty of proof online even on community tab that it exists. They refused to do it for free and said to pay 14k for replacement as phone is not in warrenty . There is no physical damage and when I asked then to reinstall the android version it worked for a few minutes. And then screen turned green again. They also refused to provide me an acknowledgement as to my device has no external damage or water damage.