Don't get all mad about it stryker: life is too short to get mad over something like this.
Just keep it. It says right in the letter you have no obligation to do anything which means; you don't have to pay them, and you don't have to return it. And to vent your frustrations over the AMA, you can go out and run it over with your car if you want, and still not pay them. Although, it would be kind of funny to run it over with your car, and then use the mailer to send it back, or attach a brick to the box and send it back, since they charge by weight.
But once again you have no obligation to do anything.
By the way, I'm not a lawyer, but I saw one on TV.