So by all accounts it looks like this is dead (or am I wrong?) but in an effort to keep it alive, I have found a method to get past the 'flight confirmation' page that provides the error and get the payment page to display, although by doing so I create a new error. With some experimentation, maybe we can figure out a new way through?
So if you force an error in the flight confirmation page (i.e. invalid country code) it'll then take you to the payment page (which you can't get to otherwise). Only problem is that you then have a invalid country code error which doesn't allow you to proceed. Seems like the type of thing that may be overcome with an incognito mode/2 browser trick of some sort... my connection (on vacation) is too crappy to do much experimentation to figure something out, but what I described above may help in pointing people in the right direction.