Cannot get my paid up letter

I had a loan with FNB which was handed over to Blake and Associates beginning of last year. Every month with out fail the call centre personnel would call me for payment and every month i made sure i stuck to my agreement. In April 2017 i have paid up that loan but now there always seems to be issues getting a paid up letter. Every time i call they promise to send it but it never happens. Its sad to know they happy to assist you if they want your money but for proof to confirm i am paid up its impossible for them and they always just sending it. I need help to get letter as i need to sort out my credit score asap. I am really not happy with their service