FNB staff incompetence

I have been under debt review for the last 5 years and paid the outstanding balances on my 3 FNB accounts in October 2022. The Debt Review Centre has only issued a clearance certificate for one account and not the other two. This is holding up the process of obtaining my debit review clearance! How is it possible that a clearance certificate can be issued for one paid-up account, but 3 months later the other two are still outstanding? My other debtors have not had any problems issuing clearance certificates.