Contract cancellation

I called Customer care.spoke to an agent.i specified that the reason for my call.was the contract cancellation process.they advised that I'm able to pay via EFT call back in 48hrs and request closure.i specified that I'm requesting the full amount due for cancellation.payment was done by myself as per amount given they have received the payment but now advise there is still a owing balance.as what I paid was for the device only.when I called as a client I should be informed of all correct information.ive been transfers from customer to detentions with a promise of a call back.i need the contract cancelled.