Cannot purchase Liscence

I'm very stressed about the upcoming Harmonia assignment that is due tomorrow because when I try to order the license Harmonia is saying that my payment isn't valid and that my order has been cancelled. This is when I try to buy it through the website, and I've tried not only my own credit card but also two of my roommate's credit cards as well, one of which he used to buy his own license, and I don't know what to do. I've signed in on my own laptop and also his to see if it changes anything but nothing seems to be working. If you know anything else I should try please let me know