One common thing is if you have already purchased the game, if you see the eLicense screen, you should be pressing the smaller License button just below the "Buy" button. That will allow you to enter the order ID that you should've received in the email above.
Also if you have had a failed transaction, most banks are going to show a hold on your account in the amount of the transaction, this hold will go away on it's own in a few business days (typically one or two; although they warn you it can take 5-7 business days). There is nothing that Grey Dog of eLicense can do about the hold, it's something that your bank does on its end, trying to reserve the money to ensure you can complete the transaction. Bank holds are the #1 cause I get for double purchase complaints.