I recently used a website to purchase flights. When I tried to pay using my credit card, I got an error message on the screen that said that the transaction couldn't be processed, and my card wasn't accepted. So I then completed the purchase using another payment method. However, when I went back to look through my bank statements, I found that my credit card HAS been charged. Who do I go to first about this, the travel agent or my bank? What rights to I have under Australian Consumer Law?