Landline cancellation

Well what can I say never known a company with such shocking sevice to the public. I have tried to cancel my landline since January, emailed,phoned,chat line,no luck nobody phones back or returns email correspondence. I have sent in my cancellation forms 3 times , but get email back every time with a no reply to cancel my adsl line with my provider which was done in January. Still getting account every month to be paid for a sevice I dont have anymore. My credit rating means nothing to them if it goes down the tubes. Now I know what it feels like to be held to ransom