Tries to purchase license - blank page at payment

I'm trying to purchase a license of Norton 360 V.6 with a student discount. I've logged in to my norton account and have the product in my shopping bag. But as I confirm and am supposed to reach the page where I fill in my credit card credentials - I am met with a blank page and can not complete my purchase.

 

I've tried with both Chrome, Firefox and Internet Explorer. I think it worked the first time I pressed. But then I wanted to go back and check something, I just pressed back in my browser and I haven't been able to load the page since.

 

Here is a screenshot of the blank page (with my favorite-bar painted out): Capture3.png

 

How can I complete my purchase?