Error Code and no one being able to assist

I want to reduce my overdraft every month starting this month. Since Friday I keep getting the following error: Failed to decrease Credit Facility Limit. Error code: 14323

But no one seems to help me at FNB, I get told I have to go into the branch. I cannot simply go into the branch. it takes an hour out of my day for simple things such as picking up a card. Can imagine how long I would have to sit to do this in the branch. I spoke to a virtual banker and just kept getting transferred from person to person and no one can help. Seriously after 9 years of being with FNB and you cannot help me with an error code on your site? Really what options do you give your clients who want to reduce their credit. Not happy with the service given.