Apple - Warranty Not Being Covered for my Iphone XR

Purchased iphone XR worth Rs ***** in Feb ****. Started facing low volume issue with the receiver. Took phone for service on *th Oct **** to iplanet care , inorbit mall, whitefield , bangalore for repair under warranty. It was checked by the service center and i was told that there is a hardware issue with the phone and they need to send the device to ARC get it repaired. I contacted service center again on ** th and i was told that the ARC has mentioned that the display is *rd party hence warranty is void and i need to pay for it. Essentially i was not clear what they meant by it. After asking several times asking i only got the clarification that i need to pay. My phone is still in warranty and there is a hardware issue which needs to be fixed by them without any cost. They are trying to push the cost to me by alleging that i have got the device repaired outside somewhere which is not the case. My device is just bought in Feb **** and its the first issue with the device so there is no question that it was opened ever for any repair. secondly if it was ever repaired outside i will not be foolish enough to claim a warranty coverage on it.