HORRIBLE CUSTOMER SERVICE FROM A STORE MANAGER

Hi,  In early January my husband, mother in law, and myself went into the AT&T store located at 4964 Lapalco Blvd Suite B Marrero, LA 70072. The manager of that store, John Berger, assisted us in switching over from Verizon. At that time we were explained that day we would receive a trade in credit for our phones, which we did, and then told us when I received my final bill from Verizon to bring it in and he would help me submit it so that we could get the money to pay off Verizon. He told us it was up to $650 per line. I went on my Verizon app and we looked over everything together and how much I still currently owed to Verizon. He informed us that it was well under the limit and it would all be paid off. ($760) all together. After submitting the bill at a corporate location I was informed that was indeed not the way things worked. You minus the amount you received the day of for your trade in  form the $650 and you receive the difference. I am now only getting a little over $100. I will owe Verizon over $600. I went into the store for weeks trying to question the manager why I was explained things this way. He was never there. A few employees took my name and number. I never received a call. I continued to go into the store  and call. Finally, weeks later I was able to speak to him over the phone. I inquired about my bill which there were activation fees that he promised would be waived (he did take care of that) and then I questioned him on the incorrect information. He immediately became  mad and rude. cutting me off telling me no no no mam i know what I said and I know i was clear about it. I told him no sir you told me (repeated what he said) he  then said are you calling me a liar? I said no but I, my husband, and mother in law heard the same thing. Would you switch companies knowing you would owe another company $600? He laughed at me. I told him that I did not appreciate his rudeness and now because of his lack of knowledge I owe a lot of money I don't have and it was going to end up in collections and on my credit. He said that wasn't his fault and he had proof of what he told us. I asked him to show me the proof. He began laughing at me again. Responded by rudely saying I could make an appointment with him and that I don't remember what I was told. I  told him I did in fact remember and so did my husband and mother in law. He laughed again and again. I told him i was highly disappointed and he should not be a manger of a store. I wish I could get the money to pay off Verizon but more than anything this joke of an employee/ manager needs to be taught about his products and how to treat people. Of course I do not want to go into the store an talk to a person that laughed at me and accused me my husband and mother in law of apparently not knowing what we are talking about. I wish I had never switched my wireless over to bundled with my other services. This is just totally unacceptable. SO MY END RESULTS IN MY CREDIT GOING TO CRAP BECAUSE A RUDE MANAGER DID NOT GET PROPER TRAINING.