vodafone mobile v freeview TV

[TvrTone]

Hi I know this will get moved, but before it does cannot anybody explain the following

My step-daughter's mobile is on a vodafone tariff and the minute she uses the phone, wherever she is in the house, it starts to interfere with the tv signal. If we are watching freeview it becomes pixelated and freezes the picture, and if we are on terrestial tv it produces distorted lines accross the sceen. My wife and I are on 3, our phones do not not cause any problems, nor do any other tariffs such as O2 or orange.

Any suggestions, is there anything I can buy that can reduce or elimate the problem, because as a teenager, she is on her mobile most of the evening which makes TV viewing a tad frustrating!

Thanks

Tony