Vodacom Contractual Cancellation Process

I have issues with cancelling my contract. I had a cellphone contract with Vodacom which was due to expire at the end of August 2023. In July 2023 I contacted Vodacom and advised them that I have no intention to renew this contract. I also highlighted how in 2020, when I took the contract, Vodacom refused to link my cellphone number (which I have had for more than 10 years) and decided to allocate me a new number. I have never used that number, I threw the sim card away. Now, after my cancellation, this agent wanted to coerce me into getting an upgrade. I advised her I would sleep on it then decide. The very next day I called Vodacom and advised them I have no intentions of getting an upgrade please can they cancel my contract that ends end of August 2023. Now in September I received am invoice, Vodacom has charged me R347.50. I called in last week and asked what is it for? I am told, to my shocked that it is for an upgrade. I have not received anything from Vodacom relating to an upgrade, I do not even know what I have been upgraded to. I request immediate cancellation. After that I received an SMS stating that my cancellation will be processed on the 31st October 2023. I call Vodacom again, to query this. They advise me that I am due to pay R347.50 in September and October 2023... I asked why? and no one can explain. Vodacom are effectively charging me because their agents did not process my contract cancellation in July but instead processed an upgrade that I am not aware of.