Buying zp through Amazon

I personally have not heard of such a thing being possible, although someone more versed with all the payment methods might be able to say something with more certainty.

EDIT - I guess, you COULD redeem the Gift Card and buy a Rixty Card or something along those lines and then redeem that. ...Which flies right out the window if you read that "You can't buy Giftcards with your Gift Card Balance" clause.

Back to square one.