Calling a method from a service in another plugin from an event
Capitalization matters when you're calling services. Try updating this line:

$enquiryModel = craft()-&gt;contactformextra-&gt;newEnquiry($attribs);

to this:

$enquiryModel = craft()-&gt;contactFormExtra-&gt;newEnquiry($attribs);

and make sure you update that across all the places where you're calling that service. Try that, and post the results. I'll take another look if you're still seeing the issue, which may still be there; just grabbing at low-hanging fruit right now. :)