Send a registered letter, hire someone to finish, hire a lawyer, learn from it.
Where are you located?I am in the unfortunate position of having paid 90% for 50% of the total work completed. Although I would like my sub to finish this job, he chooses not to return my calls to discuss the completion. I would prefer to have him finish the job than report him to a review board. Wouldn't know where to do that anyway. Any suggestions what to do?