FNB refusing to close a settled credit facility

On the 28th of September 2018 I sent through a request that a revolving credit facility be closed. I received a settlement figure, which i paid immediately and was told that the account will be closed within 48 hours. It is now almost a month, and despite following up every week, FNB are refusing to close the account (there is no outstanding balance). The response I keep getting is that this has been referred to the credit manager (who obviously has better things to do). My reference number is CAS- ********** -L2Q3Q9. The staff that i have been speaking to are: Vusi Sibeko, Busisiwe Khumalo, Enoch Themba, Bongiwe Tyulu and Luyanda Bonongo. I think it is unacceptable that FNB keep this account open with the hope that I spend and continue to use it after all my requests to close it.