I purchased 1000 microsoft points with a pre-paid Australia post card for $16.50 AU. My balance before the transaction was $24.81 AU. The transaction was successful and then I tried to purchase another 500 points for $8.25 AU but it was declined. I looked at the transaction record for my visa card. The transaction for the 1000 points was not shown though the decline attempts for the 500 points were. My balance is now $4.04 AU without any other successful transactions. What has happened to my other $4.27 that I was going to use to buy the 500 points?