Discovery Credit Card Problems

After migrating from FNB to Discovery Bank, there are interest anomalies on my account. I have phoned discovery card at least 4 times, even put through to the products department. I was told on every occasion they would contact me back within 3 working days. every time i phoned with my ref # they could not pick up on their system that i had logged a complaint. it has been over a month now without any communication from them. This is not customer service in any form, it is like they are just trying to get me off the phone as fast as possible, not to mention that no one seems to know what's going on.