incorrect billing

I've had a cellphone contarct with Vodacom, with the contract expering month end of July 2025. I didn't know that I have to call in to request cancellation until I contacted the customer service wherein I was told that the contact does not automatically cancel itself. I eventually sent a cancellation email and one of the consultant called me to effect the cancellation with the last date being 31 October 2025. To my suprise I am being told that I owe vodacom and the account has been handed over to HP Attorneys. The insurance team is unable to convert the insurance into prepaid because. Can someone please resolve this.