Billing Accounts

You can't get through to them on the telephone numbers they given, or any other numbers they have. They just don't exist. How then am I supposed to query the final notice charges they are just charging every month, when I have already paid them. One way of *****ing money from a person. And to queries this, what a joke...you phone the numbers given, and it just rings, then it goes to dialling tone. What now!