It should be easy to get a rough idea of the monthly interest by multiplying the balance outstanding at the start of any month by one twelfth of the interest rate.
I did get an evaluation copy of an Australian bank checking software, but I haven't evaluated it yet.
There are people who will check it for you, but unless you feel that there is a significant error, their fees would not be worth it.
Alternatively, you can try asking the bank to show you how the interest is calculated. I have tried this twice and failed both times. No one in the bank could show me the calculation.
Brendan