What you are likely seeing is a pre-authorization—a common payment tool used by Uber, Airbnb, and every "pay at the pump" gas transaction. This is a "hold" placed on your account prior to the transaction, which will be removed in the event that the transaction is successful. This is not a charge, it merely ensures that your account can cover the cost of the order, and helps prevent any overage charges.
Since your order didn't go through, this amount will be credited back shortly—normally within 5-10 business days. If it has been over 10 business days, please let us know the order that this is in reference to, and we'll be happy to look into it!