Vodacom Billed Incorrectly after a cancelled contract that ended and still get billed for it!

To whom this may concern. I have2 vodacom contracts. One which expiered in October this year 2021. In July/August this year 2021 I already phoned and requested that my contract that Expires in October needs to be cancelledand placed on repaid. This has not been done and I now received a invoice with a massive amount that needs to be paid due to someone not doing as I requested. Now when I phoned again they said I first have to settle the billed for amount (which were not supposed to be there because I cancelled in July/Agust before they can help me. Vodacom please recify this matter ASAP. I will not be paying that amount. My contract that expired needs to be on prepaid as requested the first time around!