STILL BEING BILLED FOR CANCELLED CONTRACT

On the 3rd of December I wrote a report complaining about a cancelled contract that I am still being billed for. I received a call from the social media people and I was promised that my cancellation was sent to their cancellations department. a response was placed on my report claiming that my query was resolved. This was not the case. It was just another claimed 'escalation'. Mind you, I had been billed R982 for November, and R656.40 for December and I WAS BILLED AGAIN R656.50 FOR JANUARY ONLY THIS TIME I AM PAYING FOR TWO CONTRACTS AS THE OTHER IS A NEW PACKAGE. I cancelled the old contract on 3rd December and was told it takes 20 days to process. It's the 2nd of February and the accounts department is not answering any calls through the customer centre. WHY AM I STILL BEING BILLED???