It seems that Demon Internet seem to have gone downhill in recent years. They used to be quite clueful, but now they seem to have lost the plot entirely.
Just over a year ago, the local telephone exchange was finally upgraded and I was able to get DSL. I chose not to go with Demon; I used Andrews & Arnold instead after they were recommended to me. (I've been very impressed with A&A -- real IPv6 connectivity (with native IPv6 over PPP on the DSL line now), as many Legacy IP addresses as I can eat, proper delegation of reverse DNS and fast, knowledgeable technical support, which is also available on IRC.)
In January (11 months ago), I mailed Demon to tell them that I no longer required the dialup account which I'd been using. However, since I wanted to keep the Demon hostname which was associated with that dialup account, I wanted them to switch my father's DSL (which was still with Demon) to use that account. They replied, saying that "a representative will be in contact in due course".
I reminded them occasionally through the year, but nothing ever came of this. In September, I mailed them again, this time telling them that I had cancelled the direct debit for the dialup account in an attempt to encourage them to act upon my request.
In November, they called in a debt collection agency to attempt to collect payment for the continued service on that same dialup account, which I haven't wanted for almost a year now.
Their debt collection agency, a company called 'First Credit', took to calling my mobile phone with prerecorded messages giving no details but saying that it was important for me to call them, giving an 0870 number -- a number from which they profit when I call them. That's an interesting scam in itself, and not something I expect from a legitimate business. I originally assumed it was just a scam, in fact, and ignored the messages completely. They also sent a text message with a similar request, and since that was from a normal phone number I did reply to it. I told them never to contact my mobile phone again, but gave my email address in case they had a genuine reason to wish to communicate with me. Nevertheless, the abusive phone calls continued -- and I even accidentally answered one while I was in Germany, so I paid international rates for the pleasure of hearing a message asking me to call their for-profit phone line. First Credit's web page says "We aim to negotiate and resolve with professionalism and integrity". Their behaviour doesn't really seem to match that statement.
Tired of this, I chased Demon again. Now they tell me "we have no records in our database that you have contacted us to cancel your dialup service". That's interesting, since I still have their original replies to my email from January. Either their database is very poorly kept, or they were directly lying to me.
They now seem to be under the delusion that there is still a chance of me paying the "outstanding balance" for the dialup service for September and October. I find that somewhat unlikely.
I've now switched my father's DSL to A&A too; I don't think I want anything more to do with Demon.