bad service

I'm writing to request a paid-up letter for my loan account, which was fully settled in 2017. Despite numerous calls and a branch visit, I've yet to receive the required documentation.

Details: - Account Number: *** - Account Type: personal loan - Closure Date: 2017

I've been consistently told that the letter would be sent within 5-7 working days, but it's now been almost two months since my initial request. I urgently need this documentation to clear my name.