In response to Oneeyedvic, perhaps things have changed or maybe individual companies keep their own blacklists, but 8 years ago I moved into rented accommodation & had major problems getting re-connected to BT. I was told on numerous occasions that as the previous occupiers had been bad payers, the address was subject to credit restrictions and I would be required to pay a deposit (about �200 if I remember correctly) with call limits being placed on my account. It was only because I had been a BT customer for almost 10 years previous with a perfect credit rating and because I persisted with several phone calls to BT that I eventually got connected as normal.
Sorry ALM1706, doesn't really answer your question - all I can say is if you're having trouble with a particular company you could ask them if you're on a list of some sort? Oh and never take 'No' for an answer!