What game were you trying to purchase, Laurette?
The reason I ask is because if it is the Daily Deal game, for example, you can only pick it up if you pay the $2.99 sale price on the day that it is actually a Daily Deal, even if you have game credits available. You have to wait until the next day, when it is no longer a Daily Deal, and then it will allow you to use a game credit on it without paying anything else.
In my example above, there's nothing dishonest about it. When a game is the Daily Deal, the price is fixed at $2.99. If you want to get it with a game credit and pay nothing more, wait until it is no longer the Daily Deal.