Sony KV32FX65 Colour patch

18 months ago i bought a Sony KV32FX65 100hz TV, after 4 months i noticed a purple haze in the bottom right corner of the screen (More prominent with Orange & Yellow images).
Sent back to Mastercare who had it for 2 weeks, degaussed it checked the purity and sent it back saying they found nothing wrong. As soon as i got it back the purple haze returned.
Degaussing clears it up but only for about 1 hr, sometimes not at all, i am told that magnetic fields are to blame, i have no external speakers nearby. Why doesn't the haze move when i move the set in another room and rotate 180 degrees? Before the Sony i had a Phillips matchline 32" 100hz and had no problems.
Has anyone else experienced this? especially on this model.
Also where do you think i stand with getting the TV replaced.
Thanks
Ian