Unauthorised charges on a cancelled policy - month 2

I cancelled my insurance with Vodacom at the outset of Corona - it remained cancelled then in August billed will me for the service and reinstated the policy - i had not requested this be done, I called they assured me it was a system error - it would be reveresed in 14 days. This month re reversal and a second policy charge on a cancelled policy is on my account - What do i have to do to get this resolved???