I was having a word with one of my engineers in London yesterday and Demon's name cropped up then. As said by Jason earlier, they are not the worst by quite a long chalk, but I'm afraid their support is right up there with Pipex and the others - completely pants.
If you detail the faults you are having, we may be able to help, but this is not a forum for free technical support!
SHARK!
For every positive action, there's an equal and opposite government plan.