@starling153 it'll be an issue with your buildings distribution system. We used to have a similar thing in our old flat where something would trip a circuit and we'd loose our terrestrial tv, we were also on BT TV at the time but the trip would knock out the aerial feed to our flat and only our flat....
The building will most likely have a single external aerial which is then distributed internally by a powered system. It's something for the landlord or building management to deal with.
