No response on settlement discount

I am deeply disappointed by the treatment from Standard Bank and its collectors. I have been receiving SMSs saying that I qualify for a settlement discount however when I request a statement of balance I have been sent from pillar to post. How am I going to settle an account if I don't know how much is it that I am owing? I don't receive statement from the collectors when I request it instead I am met with an attitude by SBM collectors. I have numerously called Standard Bank and requested call backs with no win.