Refuse to send paid up letter

My Identity account was handed over to Daly credit corporation because i was unabale to pay by that time. They kept on calling me until i was financial stable then i arranged payments with them so i can settle my accounts. My last payment was on the 29th of February, I called them after debiting the last amount that was Due and they confirmed that it is paid up and. Should wait for 6 weeks they will send a paid up letter. 6 weeks has passed I've never heard from them, I called them so many times requesting my Identity paid up letter they are telling me many stories that they have badlock,that the account is pending for close since from 1st of march until this day. The other day i called them they told me that they will send but they never did. When calling them their consultant will tell you different stories every now and then. I want the paid up letter because i want to use it and i don't know why they refuse to give it to me because I have settled the account, I don't owe them anymore.