Can't buy usb licence

I have been trying to buy second usb licence for two days now, but it always ends up with following error (right after I've added my Visa details and clicked "Process payment")
"500 - Internal server error.
There is a problem with the resource you are looking for, and it cannot be displayed."

Can you see what's the problem?

I was again trying to buy new USB licences, but same error! Can you please help me? I'm trying to bring money to you guys!

I think the general advice in such a situation is to send an email to

Thanks. There have been some issues with our server over the last few days. Please try again and if it still fails, drop us an email as Lxp said above.