I'd second Andrew's suggestion. If you don't want to totally switch to online payment, you may be able to do just this one-time payment by calling and explaining what happened--er, or, what didn't happen as planned, that is. Late fees vary, but all of them are going to be more (probably WAY more) than whatever small charge there may be to pay this way once.

Glad to know you made it to SD okay. I pulled up the forecasts for E-ville and it was looking awfully bleak. Enjoy the mild temps and sunshine!