I have ordered a thing online that is over the price on my moneycard.?

I ordered this game and I forgot i only have 10 dollars on my greendot visa moneycard so it was 15. It is not the personalized card and what do I do? I am sorta panicking about it because I don't wanna owe them money on a card that I can't put money on ever again unless if I order the personalized card through the mail. Can someone explain. Thanks.