Credit card balance possibly incorrect

I have only had my FNB Platinum Card since August 2015 and I have noticed inconsistency with my available amount. I am also confused with the online transaction history view, there is no balance column per transaction which makes it impossible to understand and when I download all my transactions into csv format and sum each month there is a few thousand rand missing which I would like FNB to please create a document for each month with an opening and closing balance up to my last transaction so I can compare it with the data I downloaded in CSV format. I would also like FNB to fix the online banking statement view to show opening and closing balance and view or download statements per month. Also please show the balance per transaction as this feature works for bank accounts but not my credit card. Im not sure if the missing funds is as a result of bugs in the online banking statements or the downloaded csv file?