My TV suddenly decided to change the shade of Sians face to a greenish purple hue this morning and since then - this annoying patch has steadily grown to cover 90% of the screen

I assume that my TV needs degaussing - How much will it cost to get this done ?

Alternatively - I understand that it may be a Thermister that needs replacing - again - what is the likely cost ?

The TV is a 5 year old Hitachi - in case this makes any difference