Debit Order Cancellation not done

I cancelled my debit order on the 4th Jan and was assisted by Penelope Mnisi and I received a confirmation sms notifying me that the debit order has been cancelled.I made a direct payment on the 22 Jan using the app and paid the balance I owed which was around 4600 and on the 23rd Jan a debit again goes off my account.Called and the lady that assisted said to me on the 4th it was not done but she will do it for me and she suggested that I reverse the debit order with my bank because I needed a refund which I did.The refernce number for the 24th is ***.Now Vodacom says I owe 100.88 for a bounced debit