Something about this situation just doesn't add up for me. If you had a bad phone, wouldn't that have been covered under your maintenance agreement? If it was, and you made the mistake of buying a replacement phone through some other source, I don't see why the installer would get all bent out of shape about not having to cover the cost of that phone himself.

In any case, you'll need to find another NEC authorized dealer to service your system for you. You really don't want to take on the responsibilty of that NEAX all on your own. The "Installers" link at the top of this page will take you to lists of interconnect companies, that's a good place to start. You can also post a request on the "Request and installer" forum on this board. Good luck!