Sorry about your issues. The quality control really must be pretty bad on the PW's. I have small area of light on the lower left hand corner, but it's pretty slight and doesn't bother me really. I only see it when I'm in a dim room and the light is up high. Not sure if this is the same as you're talking about.
I wondered if it might be a defect, but watching a bunch of videos on youtube I see the same thing on all the videos where they show the Paperwhite in a room with the lights off so that put me off calling customer service.
Yours sounds like it might be a brighter patch. I'd be curious to see photos. Other than that, I have no other issues with mine.