I've been in your shoes several times before and have had very good success at resolving matters over the phone (with Delta, American, and United). I suggest that you call the website support number and, if that fails, MP. Be sure to emphasize (exagerate even) that you would already own the tickets right now were it not for THEIR sketchy website. FYI, even though my track record has been pretty good in this area, I had to plead my case to multiple people in all cases. Good luck!