Incorrect Credit Information for Security Check

I have been using FNB and other major banks for decades, both personally and in my employment. I opened another FNB Business Account for myself about a year ago and as it has been dormant, I have forgotten my login details so I called FNB to obtain my login name only. They proceeded verify me by asking security questions based on public credit information which I answered correctly but they failed me saying I only got 67% correct which is incorrect. I requested and spoke to a manager & he was of no help either even though I pointed out their information had to be incorrect. He was not even able to go over the information to establish the validity of their questions. I pointed out that I do not make use of any credit at all so the FNB information cannot be up to date nor correct. Furthermore, often I have to contact the bank that I use for my personal account and am exposed to similar security verification which I have never failed.

Very disappointing from my preferred bank