Incorrectly billed

On the 29/04/2015 I received my bluebean credit card statement for April 2015 which I did not understand at all. I said the balance brought forwaed is R18056.26, I paid R2500.00 on the 07/04/2015 which was supposed to bring the balance down but insted the balance was increased. The outstanding amount was then R18233.70. I called the customer service on the 12/05/15. I spoke to Zama who was not able to explain because she also did not understand why did it increase instead of decreasing. She kept me on hold for more that 20 minutes because she needed to ask her supervisor until the phone was cut. I called back and spoke to Liezel who also could not explain the extra charges. She then took down my number and said she will ask her manager to call me back but that did not happen until today but then luckily Zama called back saying she tried to make sense of the statement and apparently I owed R25000 before I paid the R2500. Where is the R25000 on the statement? Why is it she can see that and it is not on my statement? Is Standard bank doing some kind of *****? I refuse to pay money that was not shows on my statement.