Absa never took NO for an answer now we must pay for the fees incurred

A few months ago we requested that the credit card be cancelled. They told us they will give us 6 month fee free if we change our mind and want to use it. We never used it. Someone phoned us somewhere in January or February and asked if we want the credit to which we said NO. They never cancelled the card as per our instruction. Now there is a fee of R274.90 outstanding which they want us to pay to cancel the card. WE NEVER WANTED IT AND TOLD THEM NO THANK YOU! Now they refuse to write off the outstanding amount. Why must we pay for something we said NO to in the first place. I want them to write it off and STOP HARASSING US PLEASE!!!