Vodacom extra charges

I called vodacom to inquire why I have a bill or R200 when I have an R90 contract and they advised I purchased a Norton subscription on the app. I have no knowledge of this subscription and vodacom is charging me for a subscription I did not take up. They have cancelled the subscription but will not amend the bill for this month. I did not receive a debi check mandate to amend my debit order, I did not receive a statement to show additional subscriptions and I did not receive any formal communication that I have an additional subscription. They could not even tell me what is this subscription. I am very upset