C903 has a bruised screen coming thr...

C903 has a bruised screen coming through on the top rh cnr - this phone has not been dropped or any other trauma imposed. The first phone had a bruised screen right down the middle of the phone, this was discovered when my partner plugged it in for the first time to charge it up. They replaced it, but only just four-weeks down the track this one is showing the same fate. Could this be a prob in the SE production line or packaging?? They are refusing to replace it even though it is under warranty. They quote $250NZ to replace the screen myself (cheaper to buy a new phone). With regard to the bruising, how long will it take for the screen to be unreadable?? or does it stabilise.