FNB negatively affecting my banking experience with a account that is negatively affecting my banking with them. With this account number reference ***. The account negatively effects my loan applications but no one can tell me what this

Hi, for years this account number *** has been negatively reflecting on my FNB account. I can't get any business funding and I can't even open a personal account with FNB? This account appears nowhere, not on my mails, not on my credit score. Nowhere. FNB also can't tell me what this is? I need information. Stop wasting my time. Or I will switch to another bank.