Trade in credit program

hi

i was falsely led to believe from a licensed professional who sells phones for different companies in Walmart that I would be able to trade in my phone, receive credits and use them towards buying my phone to get it unlocked because I was with cricket/boost for 17 years before they started all this installment crap. My device is less than 72hrs old and I’ve been wanting to return it but they took my phone for the credit at the actual art store, my payment is outrageous I went from a $30 boost bill which went perfectly with what I used my phone for in general never exceeded anything. I’m so (Edited per community guidelines) I want my old phone back I was led differently after that company in a Walmart store and then att took my phone all within 24hrs. My first bill was looking like $200 which is 6x almost what I paid before. Even the activation is more than my monthly bill. I know they played me at att because I specifically told the guy I didn’t want coverage and yet it was on my plan. How can this be corrected? Like my old iPhone was in perfect condition 3+ years old same screen protector since I bought. Not a scratch. I did however put a new battery in it a few months ago through an apple retailer. Before I start hanging up on customer service for the next 12 days straight because of frustration like what can I do? These people’s jobs affected for lying? I mean this is serious to me and it’s so late that’s why I came here first because I can’t even fall asleep. These people should not sell phones and the guy at att did (Edited per community guidelines) near the same thing changing my bill and what not. Please any advice especially from att rep