Paying money I know nothing about

I had 2 contracts with vodacom...contract A was due for cancelation and contract B was a year from the expiry. On 12/02/2021 I asked for contract A to be closed while I asked for contract B's settlement amount. I was told that account A was closed and given the amount needed to be paid for B to be closed. I paid the amount and closed account B. So I'm convinced I'm done with my relationship with vodacom. On the 19/02/2021 because I keep reading that vodacom is problematic with closing accounts i decided to ask for paid up letters with vodacom to only be told that contract A ( the one which has reached maturity) is not closed and i have to pay R600 and some change at the end of the month when I asked the consultant (Maria) why I had to pay that amount while I asked for the settlement of my account she told me her system is having a glitch and had to come back to me to refer me to the accounts department. I was given a number that I can never get through on and am dumb struck and wondering why I have to pay money i thought I settled