Their job is to suck your soul out, give you peanut shells, and kiss asses to their clients.

Correct. And your job as a freelancer is to do the same thing. I feel slightly sorry for this guy, but his failure to get any kind of deal memo or contract in place shows him to be an amateur.

EDIT: I extended my original comment as it was so brief as to be potentially confusing.

As for ripping off his design for the poster - nope. I recognized the visual concept immediately as a fan of Chan Wook Park's original Oldboy of which this is a remake. Here's a publicity still from the film: http://byt.wpengine.netdna-cdn.com/wp-content/uploads/2013/0...

So the notion of a man emerging from a packing case in an empty field is part of the scripted action of the film, not Mr Garcia's idea. The image of a woman in the background is also related to a story element (which I'd prefer not to explain lest it spoil the plot) and I'm willing to bet she appears with similar costuming in the film. The fonts, layout and content of the textual elements are wholly different And far more inspired by the publicity materials of the Korean original.

The marketing company should not be employing Mr Garcia's material on their social networking pages. However, it's unsurprising that whoever is in charge of the social media marketing would assume that any and all art assets were the products of a work-for-hire agreement as that is normal practice within the industry. however, this also has to viewed in the light of:

Early in the conversation the agency told me that I could publish the work as my own for the “exposure” so since I knew I was not going to getting paid I put the posters in my portfolio.

This is a grey area. An industry portfolio is generally understood to be for exhibition to other clients. Standard practice for cinematographers, production designers and other keys etc. is to either a) negotiate a release for copyrighted materials to be part of a public demo reel or b) to limit access to the demo reel to potential clients, eg by using password-protected videos on vimeo or sending publicity stills privately through email, samples of recorded dialog (if you're a sound person, as I am). And so on. Again, this is the sort thing that is usually established in a deal memo, and such a normal situation that it's typically boilerplate.

Without such an agreement, any claim by Mr Garcia that the pictures in his portfolio were official key art in any capacity (even unused) verges on being an implicit appropriation of trademarks, publicity rights, and/copyrighted material (to they extent that they employed any elements from production stills etc.), as distinct from mere 'fan art.'

Now, it's bad that Mr Garcia got no contract in place but I really think there is a bit more to this story, because the first thing any producer learns on anything but the most amateur-hour production is to get legal releases for any and all performances or copyrighted material on a work-for-hire basis. contractual relations are the lifeblood of the film business and even small indie productions with budgets of only a few thousand dollars use boiler plate agreements.

I'm not a lawyer, but I have worked in this field for a decade and I've been party or witness to disputes about ownership of work from both sides of the table. I don't find Mr Garcia's version of events entirely persuasive.