Settlement letter

I owed Nedbank 27 thousand and something, i was given a settlement amount of R21740, I paid R2170 amd advised it will take 7 working days for me to receive a paid up letter, i phoned again as i didnt receive any letter, Kgoitsimang advised that it will take 21 working days, i don't understand why they not telling me the story and that i must wait for 21 days all of a sudden, i paid what i was supposed to pay, i am really not happy about, i need the paid up letter so I could sort out my things