If someone missed the deadline for such a long time, I'd just blow them off and wouldn't pay them anything. However, what should you do now? I would try to push your current programmers to finish the job they started, and give them an ultimatum. If they don't finish the site within a certain period of time, you won't pay them a cent because they didn't deliver what they started and promised to deliver. If they do finish it, you'll pay them the whole amount.
If everything falls through, be sure to find a reliable company/freelancer who will do the job right. I think there are some good programmers here on NB. Good luck!