Vodacom insurance cancellation

I have a vodacom contract and cellphone insurance with Vodacom. On 11August 2020 I cancelled my insurance. Later they still billed me the for the insurance. I decided to pay for August . In September they billed me again for the insurance. I called the customer care and they informed me that the insurance was not cancelled on the 11th of August. For some reason their system did not update the cancellation. I then refused to pay the insurance and only paid my subscription fee. Everyday I get calls from Vodacoms automated machine telling me my account is in arrears. I keep calling them to sort out the problem. Every time they insure me it is sorted out...but it is not. I still get bills saying I am in arrears. I am so frustrated with them. This will effect my credit profile at the credit bureau because of some idiot who did not cancelled my insurance when I requested them to do so. Vodacom is surely one of the worst service providers ever.