Vodacom early cancellation is a waste

On the 10th of May I contacted Vodacom as I wanted an early exit to my contract. By the 13th they had already send me the cancellation fee and I paid the money and confirmed the contract was cancelled. Today, the 3rd of June Vodacom debited me? I don’t know why and for what? Trying to reach their early cancellation division was futile as no one is responding. What’s the point in cancelling, paying the cancellation fee only to then still be debited? Now if I reverse this debit order I’m the one who will have an adverse transaction on my credit profile all because of Vodacom’s incompetence