Think that's gonna need a screen replacement mate
I had same problem on a 60" hitachi plasma years ago and the only fix was a screen replacement and would of cost pretty much the same price as buying a new TV. Don't know how much a screen would cost nower days for yours,you would have to get a quote and go from there
With the World Cup coming up think there'll be a lot of deals/sales on TVs so you might pick one up a bit cheaper on sale. Maybe have a look at Argos as they have different offers each week and if you get a store card you can pay over 9 or 12 months so your not paying out a lump sum in one go
I think the brick method can sometimes make the lines seem slightly worse than they were to start with. The breeze block method however is much softer and less lightly to scratch the surface as it passes through the screen.
I always take out a 5 year Warranty and nearly every time i have had to claim on the cheaper tvs I am Using Panasonic at the moment so far they have been very good no problems and come with 5 year warranty as standard