Sorry about your trouble. It's hard to know to know who's the bigger culprit here: Odesk or True Accord. I had a run in with both parties, too, over a debt that Odesk eventually acknowledged wasn't owed after a lawyer intervened at length. Initially, Odesk said, "get lost," and True Accord kept spamming away desipite receiving many requests for debt validation. The e-mail harrassment didn't stop till Odesk told them to knock-it-off. True Accord is violating U.S. Debt Collection and Anti-Spamming laws, too. BTW.
You could report these guys to any number of U.S. state and federal agencies for illegal debt collection practices but that's a hassle. I also think their conduct borders on cyber-stalking or cyber harrassment but reporting them to law enforcement for doing that would be time consuming, too. Instead, I'd go after them for all the spamming they do.
True Accord's domain is presently hidden by the domain privacy service domainsbyproxy.com that does a lot of business with GoDaddy.
Domains By Proxy's terms of service clearly state that it will not tolerate spamming . Therefore, I suggest filing a spamming complaint about True Accord through the form on its website. True Accord switches up IP addresses a lot so they can keep harrassing people who have tried to block their messages. Therefore they're hard to track down in that sense. But hopefully they'll end up on on some ISPs' blacklists if enough folks report their spamming to Domains By Proxy.
Good luck to you!