Having the same issue right now as well. Trying to pay the immigrant fee. Embassy suggests I pay this before flying out (flight is in 5 days) so I really hope they get it together before then.
Absurd that they have no alternative methods to handle this, absolutely no email to get support, and not even a phone number you can call from outside the U.S. (even if you DO call from within the U.S., you're just dealing with an A.I. receptionist..)