P2317H, eBay, display screen coating peeling

I purchased a Dell P2317H from eBay, and the P2317H is good overall. The only problem is that on the top of the P2317H there is a little square of white light due to part of the polarization filter (display screen coating) being peeled off. Does anyone have any suggestions on what I should do? How to replace the filter to make the P2317H good as new? Any replies are greatly appreciated!