Service Cancelled, Ignoring REFUND Requests

Force Telecoms cancelled their service as of 1 October and did not inform me. An invoice was sent as usual in advance for October and I proceeded to pay it. Then on 1 October my internet connection goes off and 3 days later I reach them telephonically only to be told their service was cancelled. Now 17 days later they do not respond to any emails or pick up the phone and have not paid my money back. The cherry on top, they send an Invoice again for November knowing they have cancelled their services.