q.2. interference on slave tv

[flaming]

I've still got the interference on the screen of the slave TV when it is on the 3rd floor. On the second floor the picture is now fine, better than it was before. The worst is right under where the Satellite aerial would be. If I cart the equipment to another position away from the usual plug-in area, the interference is only faint on screen. So it looks like the communal satellite aerial on the roof causing it. Previous to mid Dec. it was OK plugged in at that spot. What I could say when I phone up please? I am sure the company will try to fob me off as I'm not a client. Presumabley my "normal" aerial goes into the same pot, and I wonder how I stand about it all. Surely I am allowed a normal TV aerial without having to pay? Coincidentally Thames Water sent a letter round informing that the new plastic main installed no longer earths the block like the old metal pipes did. Surely that has nothing to do with it? Any ideas please?