I was once given a Wal-mart Money Card, which is basically a prepaid Visa card. $3 fee each month, $3 activation fee, etc. I said screw it and bought myself an Amazon gift card with it, and applied it to my own account.
So for each card, you could do this:
1. Go here: https://www.amazon.com/gp/gc/order-email?ie=UTF8&ref_=gc_lp_4ways_email_top
2. Type $15
3. Put an e-mail address you own (not sure if you can put the one associated with your Amazon account, I always use a different one)
4. Add to order, check out using one of your gift cards
Then, when you are done with all that, just get the activation codes (or whatever) and apply them to your account. And now you have $45 in Amazon credit.
--
Zachnorn Everything = overrated.
http://img841.imageshack.us/img841/4503/qrcode857546.th.png