Do you know if it's a new shape (square rather than oblong) homehub ? If it is, then try using a paperclip or somesuch and keep inserted into the 'restore to default' hole on the right hand side about half way down. Hold in until the power light goes back to orange, remove and wait.
Also if this was a new install, it may be worth trying a different RJ11 lead, as have a spate of these being faulty round this way.