Cancelled Contract Still Active After 6 Months

Good Day, <br> <br> I am highly frustrated with Cell c, one of my contracts with them expired in Feb, to my surprise cell c is still debiting my account for contract sim card that has been inactive for years as I never used the sim card. I remember calling them and was transferred to their cancelation department to cancel the contract.<br> <br> Can sum1 help me to resolve this issue as I have paid