Deep scratch on just unboxed IPhone12

Purchased an Iphone12 yesterday (29th June 2021) from Apple Reseller in Bangalore. After unboxing and uplaoding data, realised that the screen had deep scratch in top right corner (concealed by a coating/ layer of some kind).

It looks like a scratch due due to some machine part at the time of assembly.

Reseller refuses to help replace the damaged piece. I do not want to accept this sub-standard product. What should I do? Who should I contact for redressal of my complaint and problem as an Apple Customer for last 9-10 years?