vodacom charges after contract cancellation

I have had a contract with Vodacom over the past 2 years and it ended , however after i have cancelled my contract with both numbers as the one phone was lost and the subscription was put as a prepaid phone, they are still charging me for airtime that i have not used. This is for both numbers as i have got 2 phones on 1 contract . I have spoken to the accounts department and cancellation department on 9/10/2020 with Simelo at 10:01 . He gave the number for the cancellation department *** and i have followed the steps as per the conversation. It was frustrating as when i was explaining everything ,he put me through to another person named Telefelo at 10:06 in the cancellation department. My reference number for this settled conversation was TFHOLOFELO . To this day i still get a statement with charges after i cancelled all my ties with the contract.