Salesman cheated me

So I upgraded my internet and got a call from a type of door-to-door salesman and he was offering me a huge deal to switch my phone carrier service provider to at&t and the deals he told me in person seemed so good to be true and even after I told him that my past experiences with all cellphone carriers trying to lie and cheat me, he acted like he was different. So I trusted him and switched and got 2 new phones and a tablet and he said that he would credit me and that he would also help out on paying the early termination fees from my previous carrier but after a few days, he never replied to text and when I tried calling his number with many different phones, it just goes straight to "the number you have dialed is no longer in service...etc"

I obviously got cheated like all other service providers. Why are these sales people trained to cheat and lie just to get commission and rip people off. I'm so sick of this.