Latest update!
the brightsparks engineer will be returning next week. Upon further tests conducted live during a call to the call centre (updates, factory reset, etc.) the fact that I could receive the Sky channels for a few weeks (with the new TV box) before they disappeared suggested that it might well be the TV box all along (esp with the new "stronger" broadband download signal but no other faults "within the house") so I'll keep everyone posted....
