American Express Promises, Promises- Los Angelos California

I received an offer in the mail by American Express, stating that if I get the card there offering me and spend over $ 1,000 within the first 3 months they will issue me 25,000 membership rewards points. I did spend over $1,500 within that time and when I wanted to use the 25,000 reward points equaling $250 towards my statement they told me I had this card in the past and already took advantage of this offer, which I totally have forgotten if I did. But never the less they sent me this offer and I kept my end of the bargain but they refuse to give me what was a written offer I received in the mail. I bought a new TV figuring that the $250 they promised me would help pay for my new TV and now they tell me I'm not eligable. If I wasn't eligable why did they approve me and send me a credit card to use to make those purchases so I feel I've been defrauded. If American Express can't back up the mailing offers they send out they shouldn't have people signing up for these offers only to find out there not going to get the $250 that was promised in the offer.That's what I call a Ripoff!!