Hi there. I paid for my pre-order copy from the SE store on Aug16th and today I was billed again by the SE store for another 29.99. Why? What can I do to get my money back?

From my bank statement.

Aug 30, 2013 DIGITALRIV 29.99_V 32.41
Aug 16, 2013 DIGITALRIV 29.99_V 31.85