Debiting account on closed accounts?

Cell C has been debiting my account when a cancellation was initiated in the appropriate time as the process. Its now 3 months later and account is still being debited and the call center now advises that they apologise but another 30 day waiting period has to be put in place to cancel a contract that should have been terminated already incurring another debit of my account. CONSUMERS PLEASE CHECK YOUR ACCOUNTS WITH CELL C ESPECIALLY WHERE YOU CANCELLED AS YOU MAY STILL BE WRONGFULLY DEBITED WITHOUT KNOWING!!!!!!!!!!!!!!!!!!!