I Need Help On Google Checkout.

Ok You Guys,
I Bought 2 $25 Visa Debit Card, And I Registered It On
Google Checkout.

I Wasted Both Of My Credit Cards With 20000 ZP's Which
Cost $17.49.

Now Both Of My Visa Cards Are Now
$7.51.

But I Want To Combine My Visa Card To Make $15.01 Together So I Can
Buy $8.99 ZP's On Z8Games.

Is There Any Was To Combine The Money I Have In My
Visa Debit Cards?

Please Help Me Out.
I Want To Buy More ZP's

My Google Checkout Photo::
checkout.png