really curious who the company is (email me it if you don't want to post it here)

i've taken jobs similar to what you described - scope changes after the fact, no payment until 30-45 days after completion (though if its multi thousands, i ask for half down)

The difference being I maintain a day job; freelance to me is a bonus - money for vacation, nicer things, etc...

Sucks to get burned like that, but to me, thats a normal client... 1 mans trash is another mans treasure ?