So, 2.5 Years ago, I purchased a KD-43x7500F TV. It's been OK, but recently the edge lighting has really been bothering me. It seems to have gotten worse. There are 3 parts of the screen where the edge lighting is much brighter than elsewhere.

I called Sony, who asked me to email them a photo. It's pretty grainy but clearly shows that there is a pretty big amount of bleed which makes both top corners, but especially the top right, meaning that pretty much the whole panel is more dark grey than 'black'. 

They then wanted a photo in normal lighting situations, in which you can't really see the issue (though who watches TV during the day?). 

They have stated that according to their website, edge lighting issues that can't be seen in 'normal' lighting situations aren't warranty matters and excluded from their warranty terms and conditions. 

I feel the lighting ruins almost all dark scenes and that TV is usually watched in the dark (or for me it is?) or dimly lit room. 

What are the chances of an outcome if I decided to push it further, or is it a case of tough luck?

From Sony's Website: 

NOTE: All shipped Sony products have passed internal quality tests. Backlight bleeding that can only be seen in black images and in a dark or very dim room, must be considered within specifications. To our regret, claims for service or replacement cannot be accepted