^exactly, they probably didn't want to take a loss on the sale.
If you do it through the phone/check process it doesn't hurt the store.
Only times it can't be returned is if it is worn, or the the receipt specifically says something about no returns/refunds......I know certain HOH releases or just certain releases have that on the receipt. One reason is when resellers flop they can't take the pairs back. But I don't think the 13s were included on the no return, at least not in my store.
That's why I only buy GR's from the major sneaker stores. If I need to return it, then I can. You usually can't reurn items to mom and pop spots.
Try another FL than the one you bought those from, or go back to the one you got them from and tell them you're going to call corporate.