On their website, somewhere.. I'm not sure where. Maybe at the bottom of the page, or in some small print somewhere, there should be a 'Contact Us' link. I found it eventually when I had problems. I think you can either email them, and if they decide it's a decent enough excuse, they'll email you back. But if your problem is something their electronic bot can't handle, then it will tell you to call them. And trying to get a hold of someone over the phone is even worse. I think someone named Max answers the phone, and never really tells you what you want to hear. Like I said, Harmonix is really difficult to get a hold of sometimes.