Apple - Apple not replacing device under warranty

I ordered online on www.amazon.in on the **th October **** an iPhone X (Invoice enclosed). The phone has been giving me trouble off late and despite sending to their authorized service center, I am not able to get any resolution. Their authorized service center/repair center have cited inspection failure and are not willing to either repair it or replace it under warranty which is against the norms of the industry. This phone had a display issue and was submitted to the authorized service center (iCare, Vasant Square Mall, Vasant Kunj, New Delhi ******) on *th December **** and the display was replaced under warranty and the device was returned to me.The same display issue arose again on the **st January **** and was again submitted to the same service center. Now I understand from the service center that they are not able to solve the problem and will not fix the device under warranty because they are accusing me of getting the device modified from a third party despite the case. They have also challenged me to report them to any legal authority to take action. Hence, I am forwarding my grievance here to address my redressal as this is my hard earned money and I value it very much.