Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
Occasionally, when paying online, even with a perfectly valid credit card (or other account of rendering payment), there is a glitch, a fault, a little temporary problem, and the payment doesn't go through.
In this case... I may guess at the cause: a server fault (and thus account couldn't receive payment that was otherwise quite usable and valid), or perhaps a matter of a simple mistake, such as that you thought you initiated the payment, but your internet connection was disrupted for just long enough that the payment 'timed out'.
Depending upon who (or what company, or website, or just what purchase) the payment was for, there may be various processes of either canceling the purchase, or rendering the payment upon a second try.
But, that you 'owe a total of XX.XX' implies that you received something, but the payment is still owing. Perhaps the server fault was like that, and gave you the benefit of the doubt as to access to an e-book.
Let me know more about the payment, and I can suggest further things to do about it, in detail - depending upon what course you wish to pursue.
(If this answers your question, please rate my answer. Thanks.)