This is my personal experience with Jetstar, but it might apply to other low budget airlines as well. During the checkout process, after you enter your PayPal or credit card details and enter "Submit", if you encounter a timeout error or any other error, DO NOT TRY AGAIN! Call the airline to confirm if the order has been placed or not, or you may be left with a duplicate booking. Now if you end up with a duplicate booking, you can always call up the airline and get them to refund one of them. But the refund can take a looooonnnnng time. In my case, it took 1 month for them to approve the refund, and another week for the money to be refunded. I guess I was lucky to get my money back. Some people weren't so lucky . And did you know that 50% of Jetstar profit comes from people who buy a ticket and don't fly ? I wonder what percentage of that is non-refunded duplicate booking?