No paid letter

Probably the worst customer service experience, over promising and under delivery. I paid up the account on the 12/09/2023, I have called almost every week since then to get a paid up later to no luck. Escalated to Ansley their supervisor\teamleader, he promises to call me back never does. At some point he promised I'd get the letter before clsoe of business, no letter and that was about 2 weeks ago. It shouldn't be this difficult to get letter, meanwhile there's a balance that's accumulating interest.