Make sure it says on the item's page that it's an eligible purchase. If it is, then you can either wait a couple days to get the code like I did, or if you're impatient contact Amazon support and see if they'll go ahead and give you the codes.
But if the card you bought isn't eligible and you haven't used it, you can try to get a refund and buy something else.
edit - And just to make sure, you're in North America? I know Canada had some problems with the previous promotion because they had to purchase from amazon.com and not amazon.ca, and then they get hit with taxes, tariffs, border fees and/or whatever else nonsense that made it cost more for them.
edit 2 - Also, for me it took exactly 48 hours from the time I got my game time card until I got my item code.