Unfair listing on credit report as a result of an expired contract with Vodacom

I had a contract with Vodacom which was concluded via telephone from 2017. I signed up to take the vodacom tablet and to pay via a debit order for 24 months. I did honour all the 24 months payments and after contract period has expired Vodacom kept deducting from my accounts and I only noticed after a month and I called them to ask why there were still deducting my account they told me i had to cancel the contract because it was automatically renewed so they transfered my call to cancellation department where I told them to cancel the contract with immediate effect so they agreed to cancel. After a month after I cancelled they deducted again and again on a second month so I went and reverse the debit order. To my suprise now i was applying for a credit somewhere and was told that my credit score has changed to low because of the missed payment for these contract. I found this to be very unfair and unacceptable act by Vodacom how can they not closed the contract after it expired and not closed even after I called for a cancellation, now my whole life is affected by this Im so angry and dissapointed such a big company like Vodacom to do such an act