The pipes are likely enclosed behind another contractor's work (drywall, paint, ceilings, etc). Plus, what are you going to do with the pipes that have been cut, connected, etc. for a specific job? It's unlikely you will use them somewhere else without having the added expense of modifying them somehow. And it's very little about the pipes they installed and more about the labor they paid to install them. The best bet would likely be to sue, have a judge (or two) rule in your favor, and collect interest on the amount owed while you wait.