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If you can prove malice, you may try to sue the subcontractor for tortious interference with a business. If you had an agreement with one another that specifically forbade direct contact with clients, then by his behavior the subcontractor cause injury to your business by specifically contacting your client directly, knowing that it would detrimentally affect your business.
You may also attempt to collect part of your fees if you had a "time is of the essense" clause with your subcontractor. That is, since the project went past time, and time was vital to the job, then the subcontractor may be liable for your expenses in getting it done in time, and may even be liable for the eventual loss of the whole contract.
He is also liable to give you his designs but only if you signed an agreement that transfers his intellectual property to your company.
Good luck to you.
Dimitry Alexander Kaplun, Esq.