Cancelled Contract but bank account still debited

Good Day,<br> <br> I had two Cell C contracts that were expiring in November, I called the call centre to cancel the contracts and they informed me tat it would be and that the last invoice amount would be debited at the end of November 2015 but my account has been debited in December and again now in January even though both contracts are cancelled!!!<br> <br> Please cancel the debit order and credit me the two months back!!!<br> <br> Thanks<br> Regards