Still no settlement letter

I have recently paid and settled my account with CNA,if I'm not mistaken the full payment was made on the 10/03/2015 and since then I have been struggling to get a letter from your company stating that the account is fully paid up, I have phoned in several times including today and the people i spoke to seemed clueless to say the least they didnt even know what I'm talking about, the lady I spoke to today (from collection/legal) said she will forward this matter to Customer care and they will contact me,I asked her to confirm how they were going to contact me, if by phone which number are they going to phone if by email which email address, she didnt have any of those details and when i gave her the details she seemed a bit reluctant to take my contact details, how do i ensure that the credit bureau info gets updated?? if they can't even offer me a simple \paid up letter??? its been over a month now and this is my second post on Hellopeter and still nothing"