Sorry to hear about your troubles, seems like a total nightmare and fingers crossed you can get your parts back. Surely there are a number of members on here that are able to contact James and get at least some response on this, as for him to go dark and not respond to you or try to resolve this is out of order. If he knows where your parts are (as he's seemingly said in a previous message to you) then it's certainly not that difficult at all to get your parts back to you.
Hopefully it won't need to go legal, though given he's basically run away from these issues by closing his forum account and declining to respond to calls and texts then it does look like it may be the way you need to go.