Vodacom refuse to cancel my contract that has reached its term

I have two cell phone contacts with vodacom, I called vodacom in September 2020 to inform them that I would like to close my contract with them because I can't afford to pay anymore, the call center agent insisted that I should take a lower offer that will I will be able to pay I told her that I can't afford anything at the moment, the lady that assist me told me she will call me on Sunday to hear if I'm interested in what she offered me, my wife picked up my phone on Sunday when she called to asked if she can give us a lower contract offer my wife rep**** no we dnt want it can they cancel the contract. I than call vodacom again to asked if my contact is canceled they inform me that I need to give them notice which I did the lady told me to call after the 4 October 2020 that's when my contact will end which I did just to find out that I will be Bill again for the month of October 2020.I called again twice in the same month of October 2020 asking if my contract is canceled as I have reached my term with them they told me yes they have send the request to another department. In the month of November I saw that my contract phone is top up again I called them to asked who give them the right to top up my phone as I have asked them to cancel my contract and I give them notice, the lady told me that the first agent never did what I asked her to do i had to pay my bill again. In the months of December 2020 vodacom top up my phone again I called them and complained to the agent and aksed her why do they top up my account without asking me cause my contact had ended now I have to pay that bill again, which means vodacom does not want to cancel my contract and if I am not going to pay I will be blacklisted because of them hiring Lazy people can someone help me pls.