Account debited after contract was cancelled

MTN is one of the worst telecommunications company I had to deal with. In July 2020 I decided to cancel a data contract after they've been debiting my account for amounts that were not on the contract. I even paid an early cancellation in July already and was informed that my contract is cancelled. But on the 30 November they debit my account and when I call them I am informed the contract was cancelled on the 6th of November 2020