I just tried to purchase a game (it's a single player game) using my MasterCard Gift Card (it's a prepaid card) and it was declined. I called card services and they told me it was declined because steam made a recurring payment charge on the purchase and you can't make recurring payment purchases on a prepaid Gift Card. I can only make one time purchases on the Gift Card.

Why is Steam charging a one time purchase as a recurring payment and how do I change it?