Credit card account closing nightmare

I have been an FNB customer for many years and have not had any major problems, I always recommend them to friends and family. However with my recent experience with closing my credit card account this may have changed my mind. I phoned for a settlement amount on the 9 July 2019, to which I paid the amount over straight away while I was on the phone with the consultant. A few days later I saw there was still an amount outstanding which was a bit confusing so I called FNB back and they explained that there was a transaction that had not gone through when I paid over the settlement, which made sense and I was happy with that. When I had the money to make the further payment for the additional amount outstanding I made the payment plus a bit extra, which was on the 1 August 2019. I did this all while on the phone with FNB. The consultant I was speaking to said I would receive a call from the credit card division within 5-7 working days. I have not received any calls from FNB, I have had to call them and the last consultant I spoke to was incredibly rude and told me that I still owe, but according to my statement I am actually in credit, the said consultant made me hold for 17 minutes while “getting a manager” which never called me back. Please sort this out immediately as I do not want this account anymore and would like to continue having a happy client/service relationship with FNB.