AT&Ts responsiblity to it's customers?

I just brought a BlackJack II from an AT&T store. The sales reps sold me this phone along with a wireless package that works for regular phones, but not smartphones. I was told in the store that the phone and the package would work together. They also have a brochure in their store that offers the plan I want, and doesn't specfically exclude smartphones. Are they responsible for making the plan work because they mislead me? Or am I just stuck with having to pay the extra to make it work?