I need my paid up letter ASAP!!

It has been a week since I paid my settlement amount for a loan account at FNB and I still cannot get my paid up letter. I am sent from pillar to post being told different things with each person I can speak to. Not even the branch can help. I need this paid up letter as a matter of urgency because of a pending home purchase but I am currently stuck! What is going on at FNB? Why is it so difficult to receive a paid up letter for a debt that I have settled? Very frustrating.