They ~scammed~ the OP by fraudently getting free advertisement through twitter, by giving a promise they then broke.

Sure, we can only go on the OP's word here, so let's see what the company has to say.

Even if the OP did tweet multiple times, according to the supposed statement by the company that's fine with them, so short of some other adventurous interpretation or misrepresentation of the rules of the contest, we can probably use publicly available information on twitter to come to a preliminary opinion until the company makes a statement, and then decide who sounds more credible.

Edit: For now, this tweet - http://i.imgur.com/At4py.png - by the company kind of comes off as trying to entice random popular twitter users into participating in the contest, which seems consistent with the idea that they didn't let the OP win because of follower counts.