Telephone contract

I had a telephone contract for 24 months was paying R269. The contract has ended they still continue to debit my account with R100 . The debited my account month end with R100 I reversed and went to Africa mall to cancel, today is the 15th they debited my account double (200). They called 100 times and I told them same story that I don't need any contract with them at the moment. I am annoyed by this😡.