Still being billed

I called on the 30th of March requesting for my account to be deleted because my the contract was supposed to be 12 months. I was told that I needed to pay my arrears in order for my contract to be deleted as it had already been cancelled but could not be closed due to areas. I paid the arrears, and I was advised to call once I had made the payment in order to get the cancellation, which is exactly what I did on the 6th of April. I then received a call from Vodacom on the 24th of April confirming my cancellation which I confirmed. I then received an invoice that I am owing R1558. I paid the amount owing and it was confirmed by the accounts department that the account will be closed. I need this sorted because I have not used the fibre since the 15th of December 2025.