Cell C contract- No sim card

I've purchased an Tablet from FNB and apparently did I agree on a contract with Cell C for data but I currently make use of an Telkom sim for my data. I went to FNB to complain about an amount that goes of my bank and we've cancelled the Debit Order. The amount still gets debited from my account so I've phoned Cell C who said to me that I do have a contract with them since 2012 for data which I don't use - I don't have a Cell C sim card. I'll appreciate it if someone can contact me regarding this issue. All I want is that the contract that I'm not aware of gets cancelled. Please assist.