Paid up letter

My loan account was handed over to HP Attorneys, I requested a settlement letter paid the amounts due now that the account is paid I am struggling to get a paid up letter the agent Nomsa advised that it would take 3 -5 working days , it has now been 21 days and still no paid up , this is really fustrating as the agent advises that the delay is with FNB as they should be providing the letter