Premium increased with almost R500 without any notification.

Good day, we have been waiting for an answer from our broker for over 2 weeks now - she logged a call with Discovery Insure, but it seems we are just being ignored!! We have 2 issues here; Firstly our premium is supposed to be R2900 monthly. Last month we were overcharged with almost R500 without any notification whatsoever. We contacted our broker PWG group and they also could not provide us with any clarification. They then logged a call with Discovery but has since not had any feedback. This week there were enough money in our account for the premium, but this morning we were notified by our broker that there were insufficient funds??? and that we are at risk of our insurance being suspended?????? We urgently need answers??