OnePlus - Mobile Phone is defective and the company is not ready to take liability

I bought a Oneplus * Pro mobile phone around a year back , precisely June ****.The company claimed that the phone had a very brilliant display and it was there most important selling point. The phone I recieved was defective and the display of the phone had severe tinting issues,black crush issues and other major display issues,I approached the service center and they replace the phone with an even more defective display. I went to the service center yet again but now they were not ready to take liability and remarked that every oneplus * Pro phone is defective and has this tinting issue, however the oneplus company were not ready to take liability and also was not ready to acknowledge the tinting issue.