According to http://www.paygarden.com/brands , Golf Galaxy is on the list so it should work. Maybe that Galaxy is in an alternate universe?
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They do have an FAQ and a "Contact Support" page with a form to fill out: http://www.paygarden.com/support  In the FAQ, it says that they have telephone support, too, but I can't find the number.
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Good luck.

Home Depot works and gives a pretty good conversion rate (they are not all worth the same amount). Walmart too.

Using Starbucks had a card limit if $100 a while back. Not sure if that's still true.

Do different gift cards convert at different rates/days?  How can you tell before you convert a gift card, which has the better rate?