Trying to by points but can't?

I keep trying to buy z8 points using BOTH of my Visa cards but it won't let me. While I fill the information, the website tells me everything looks good and is correct, then when I let the thing load, it says that the option is currently unavailable (Im using clicktobuy). Is there a different way to use my cards and get points or do I have to go through paypal or buy karamacoin cards?