Dispute on Biliing

Dear FNB - I have really tried over the last 3 months to sort out this dispute amicably...but was not even afforded the courtesy of a response from any of the people copied on my emails. I settled my FNB Credit card account on 30 June 2015. Charity Nkosi confirmed in writing that my account was closed on 1 July 2015. Out of the blue on 28 July I receive an sms that I owe R257 for something purchased at a P & P on 27 July...... I disputed the transaction immediately and received NO response...I proceeded to log a ***** matter with your ***** division telephonically....and still NO response.....It is sad that I now have to seek attewntion via social media.....but I was left with no choice. Kindly yet urgenty investigate and advise accordingly. I do prefer any response from your bank to be in writing please. Copies of all my correspondences sent is available upon request. Thanks