Vodacom bill us correctly, not for your mistakes!!!

I called Vodacom to cancel my contact in January 2024 and it was not done. I thought the month of February was my last month, I had to call in 2 more times just to get the contract canceled. I received an email saying I should use the remaining units, how can I do that when I destroyed the sim card thinking the consultant I spoke to will do their job. I called again and I was told there was a system error, how do I know about vodacom's system errors as I do not work there? You want to bill me for the month of March when I have done what was expected of me, I called in to cancel the data contract and to even say I don't need that number. It can be given to someone else as it was used only for data. Vodacom stop billing us incorrectly for your for your employees errors.