Awaiting Paid up Letter For a long time

I called FNB last week to get Settlement amount, I then paid the required amount into FNB account, I requested paid up letter I was told it will be read Monday till today still no paid up letter, I called Debt in again, they told me I must wait again for Next week Monday! I have been sent from pillar to post just for requesting my paid up letter! This is totally not a customer service that I expect from a big Financial institutions like FNB