How do I submit a case? (Or contact customer support?)

I go to my cases, try to submit a case, there's nothing. I'm signed in, trying to submit a case to update my email address, but there is no way to do that that I can see. I even tried looking around online for some number to call or support email or something, and there's nothing to my knowledge; how do I actually contact anyone, instead of these endless forums?!?