Vodacom insurance

I had an insurance for my cellphone device and I called vodacom on the 15 April to cancel as I never claimed. My contract is about to finished in August, the lady I spoke to, her name is Noreen she told me that she send a request for cancelation and it will be canceled. For my surprise I received an Sms on the 1 July to state that my monthly insurance premium is going to change to align the interest rate and new premium is R84.74. According to me I have no insurance anymore I want this to be sorted ASAP. I can't pay for something that I canceled. Somebody must do their work properly.