<human>: Can you condense the text into a few key points?

I recently signed up for an American Express Premium Rewards charge card.  I'll admit, I was suckered in by the salesman while walking through the Dulles airport.  What sold me on the card was the rewards points I would get if I signed up for the card: 25,000 free points, a special airport promotion.  The problem is, the salesman totally didn't tell me about the $500 I have to spend within the first 3 months of having the card in order to get the 25,000 free points.  I even specifically asked him: "Do I have to spend money in order to get the points?"  and he said "No, you get them instantly upon activating the card."  Being lazy, I didn't really bother reading the agreement fine print.  I found out about the stipulations of the promotion upon calling American Express and asking where my free points were.  They did nothing to help me out, and I thought they were known for customer service!  My question is, would there be any detriment to my credit score if I canceled the card right now? (havent spent any money)  other question: Is there any way to get justice for the fact that I was directly misinformed by the salesman?  sorry about the ranting nature of the post.  Just a little pissed off.
<bot>: Amex told me I would get free points, salesman witheld information about promotion stipulations.  Should I cancel, or is there anything I can do to get justice for being misinformed?