PAID UP LETTERS

I posted a complaint a few weeks ago and the response I got from Capitec bank just left me in disbelief. I am still unable to get a paid up letter due to the fact that I paid a settlement amount which was obviously less than the balance of my loan account. I was offered to pay around 6k if I settle which is 80% of the balance. I did so, now Bulelani Kula is asking me about the 20%!! how is that any of my responsibility????? I requested a settlement quote and I paid the settlement amount!! how am I still banking with these people??