Hi Buffalo and thanks for your quick reply.
Yes the output is set correctly, I've discovered that the only reason the pace STB was swapped out was that the engineer thought it to be faulty and later discovered it had an attenuator plugged into the input because of my close proximity to the distribution cabinet ouside! Have spoken to telewest again and they told me to change this, to change that and they are saying they wont change this box unless its faulty, I've argued with them and they are sending a tech out on Saturday, but they have said this job could be chargable. . . . mmmmmm I'm getting pretty darn good at arguing with them, trouble is I very rarely win !
Thanks for the advice !!