eurovox signal quality between 1 and 25% ?

i have recently moved house and had virgin installed and neither my eurovox max or eurovox red will work, they both have a a very weak signal i think, when i go to the screen to do the scans it has the quality bar on it and mine is flitting between 1 and 25% and in red where as at my old house both worked great with approx 85%, does anyone have any ideas, i have tried switching cables but have had no joy but they are the cables that worked at my old house anyway