How to get a fault Iphone replaced

I purchased Iphone XR in November 2020, the next week it went for repair to banglore due to faulty camera and got the camera replaced. since then , i am daily facing issues with phone like freezing, hanging, all third party application not responding like whats up, fb, insta, phonepay, googlepay and even the keypad and messaging inbuild applications freezes. service centre denied the issue .. i shared the screen recording with the apple care and inspite of same they denied replacement or fixing the issue... tried all the ways out to rseting device 4 5 times .. creating new apple id the last suggestion.

but nothing worked.. now worried about the device as warranty is about to get over and there is no resolution provided so far.

these guys even tell they don't support any issue with third party application. .. I am thinking why those applications are there on apple store then ????? .. i hope they keep them there post validation.

I would be more then thankful, if anyone could suggest me few steps or procedure.

Thanks in advance.

Regards,

Naveen G.

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