Mr Price Mobile SIM Cancellation

I requested that my sim card activation be cancelled completely on 28 January 2018 I informed the consultant that I don't need the sim because I have a contract with Vodacom. Little did I know that the sim card is still active, on my June statement it reflects multiple airtime purchases, (No statements were received between Feb - May) I'm not sure where the airtime is being sent to. I refuse to pay for airtime that I didn't make use of. Please assist!!