Vodacom's disloyalty

My one contract with vodacom was about to end on the 24th October 2020 then suddenly beginning of October I saw that my invoice was much higher than normal, I then contacted them on the 10th only to be told that they had a system error which initiated an insurance on my number of which it's contract was about to end. I then asked them to reverse that amount and also cancel that insurance policy which I did not request for only to be told that they can only reverse it in 30 days which would be after my contract end date, I tried to reason with them that since well its their mistake why should I be inconvenienced as I am now unable to cancell that contract which is now overdue due to their inability to resolve their error on time. Their insurance consults just don't care about what they did and they kept me waiting on the line for over 30 minutes when I requested to speak to their supervisor and even cut me off. This is not the first time that vodacom failed me as there was a point when they just migrated my account also without my consent. I need vodacom to sort this matter out urgently as I need that contract to be canceled urgently.