Rewardsco sales exploitation

I have received a call from rewardsco from a man on behalf of vodacom, regarding my contract renewal and I was asked if i am interested in a new phone by an agent and i told him iam not interested and he kept pressing me to take a new offer of R250 airtime and i refused and he demanded explanation and i told him i cannot afford the phone and he told me the agent whom i cancelled the contract with did not cancel the contract and i must continue to pay a monthly installment of R320 and i advised him i have cancelled the contract with vodacom and i have received an SMS to confirm cancellation, he told me to call customer care and dropped the call on me in the middle of the conversation. Please help i am being exploited by Rewardsco Agent making sales without my consent.