Nokia 5300 Xpress
Regarding crack down of display

I have bought above mention mobile on 1st jan from nokia priority dealer, delhi but on 12th of aug in the night i leave the phone on the table & at the morning when i picked the phone there was a hair line crack found in the display screen which is increasing day by day and has almost covered the whole screen, the cell is still on warranty please advice what to do & whom to contact for the replacement.

Thax.