Discovery Health
Defaulted with no Notification

I got a letter from Discovery saying that I owe them R1706.85 . I went and pay it in Feb 2013 but they already defaulted me in Jan 2013
I feel that, according

I never receive any notification in writing from Discovery informing me of their intention to list a default payment on the credit bureau?
I never receive a 20 days notification in writing of the impending listing of my account on the credit bureau?