FNB Cheque Account: Failure to reduce overdraft online.

I have been trying for the past three years to reduce my FNB overdraft online. I even visited a branch and they couldn't help. I gave up at the time. However today, I decided enough is enough, I want to reduce my overdraft. I went on online banking at 17:00 on the 1st Nov 2022 to reduce my overdraft facility and I got the following error message: Error code: 14323. FNB come on, why can I not reduce my overdraft on my Internet Banking? After all these years, what is the issue? Why am I prevented from reducing my OD?