David, Was this work inspected by the local AHJ? Was a permit pulled for the work in question? If you feel the the work that you had done is questionable then it would be worth finding an independent inspector who can review it for you. Without being able to actually see what was done it is difficult to give an answer. As far as 370-3 their are exceptions that allow the use of plastic boxes.
Good luck, Wirewiz
Wirewiz
