Struggle to get paid-up letter from MBD

I have settled an account and asking for a paid-up letter for 2 weeks now., I spoke to 2 people on the phone requesting my paid-up letter and still, no paid-up letter was sent to me. When you call the people are so rude on the phone and the line is weak. When you call back they say that they will request the letter and email it to me, I am waiting two weeks for this, and no response back.