Failure to cancel contract after cancelation was confirmed at twlkom shop

On the 24 June 2020 i went to telkom shop wonderpark i cancelled my contrac got ref per sms. ***8. They informed me it could take a while to cancel it because of lockdown. On 15 Sept 2020 a amount was debit from my account for arrears payment due. After i had to call again a cancelation was done on 18 sept. My problem is that i must still pay for an contract that was legaly cancelled on 24 June. Telkom can have the cheapest contracts i will never in my life do any with them again