Charging for Sim Card thats been sent back closed

I was sent a sim card by FNB Connect that was sent back to FNB connect still sealed in package as they only sent a sim card with no phone and I was not happy with it. I sent it back to FNB Connect via their couriers DHL and sent them a mail to cancel the contract. FNB Connect then took 3 debit order payments which I cancelled. I then received an Invoice on the 18th of January 2016 stating that I owe them R 224.00 from FNB Legal and that I am 90+Days over with payment. I then phoned again and was told that it needs to be escalated I spoke to Kershane Jantjies the phone number is ***. I am not getting anywhere with this and hope your help could be of assistance, as I feel that I am getting charged for something I don't even have or use. The sim card is not even in my possession as I sent it back to FNB and was still sealed in the package.