VODACOM UNEXPLAINED EXTRA CHARGES ON MY ACCOUNT AND THEY WON'T CANCEL CONTRACT

I have had a vodacom wifi contract for the last two and a half years. The contract expired in July this year. I contacted the Cancellations Department to give notice for this contract to end on 30th December 2022. I was told my account was now over R600 in arrears. As I pay every month I could not understand this. I spoke to another department who told me that this amount came from 2 and a half years ago when I started the contract even though I did not see that on the Invoices. A few months ago I was told that my account for the wifi was R200 in arrears and there would be a R100 penalty. I paid this amount not really knowing how I came to be in arrears. Now suddenly I am again in over R600 arrears with no satisfactory explanation. I have paid the amount just to get rid of this Vodacom account. Even though I have paid the so called balance of this account Vodacom will still not confirm that they will cancel the contract at the end of December 2022.