I'm thinking Amex would change their minds about "who's responsible" once they hear from a lawyer. It'd be far cheaper for them to take care of what's their responsibility than to defend a lawsuit.
You know that they have to be aware of the scam, and they're the ones who fed the scammer the info they needed to rip you off, there's gotta be some law juice in this.
Much more importantly, sorry you have to deal with this.
It'll definately raise your blood pressure.
