Vodacom **********ly debited my account

In September I called in and canceled my contract for 2 gig data when the 24 Months end in November. Guess what they've debited for the 2 gig data again today. What nonsense is this? Vodacom is **********ly taking money from my account. When I called in, the agent told me that the person whom I spoke with in September did not cancel the contract and its still active. I want the money vodacom debited this month back and stop this 2 gig data with immediate effect.