Charging me for months after i have canceled my account

I have not had to many issues well i had a contract with this company but then I canceled my month to month contract in December Moved my number over to Vodacom (prepaid) After contacting customer service and explaining my situation they then said i would have to pay for January as well but this would be my last instalment even though i did not agree i asked them would this be the last payment and they then said yes. I asked to receive something in email as proof they said they were not able to do this and that i could not speak to a manager. Now i am sitting in a situation months later where they saying i have not canceled my account and gave me a number to contact for cancellation where i will be able to speak to a manager but this number does not exist. This company is *****ing money from people and there is no one to contact to resolve your issues. The only way of resolving this matter is by me going into the bank and trying to stop my debit order. I will never use this company again. So badly run.