A few points...is it definitely the TV? Can everybody hear it or just you?
Is the humming from the electronics of the set (ie is it there all the time even when the volume is set to "mute") or is it coming through the speakers (so it's volume increases as the volume of the programme is turned up)?
Sounds like 'mains hum' due to the 50 Khz 240v A/C mains frequency.
It should not be a problem so if the set is under guarantee call out an engineer , there is probably a simple solution, like a dodgy connector.