LEAVING AT&T after 20 years

I'll be leaving AT&T after being a customer for 20 years. In 2020 I sent in a trade-in that more than qualified, I had to qualified plan, everything that needed to happen for me to receive my trade-in credit was in place. I never received that trade in credit because they told me my phone did not qualify. Whatever, I chalked that one up to maybe it was me that made the mistake. In 2021 I sent another phone in for a trade in. I didn't receive the trade in credit because they said they never received the phone. When I provided proof that they received the phone, they said they received it too late. I sent the phone out the day I received my new phone and the packaging to send the old phone back. I fought and fought and fought and eventually gave up because I'm pretty sure that's what they want you to do when it comes to trying to receive a trade in credit that you rightfully deserve. Those two instances were done online. So in May of 2023 I took my son into the store to upgrade his phone and add him to my plan. He had a Samsung Note 9 that was basically brand new. I kept it in a case with a screen protector on it from the day I received it to the day we traded it in at the store. We got an s23 Ultra That was supposed to be $11 a month for 36 months after we receive the $22 trade-in credit per month after the three months of billing. 2 or 3 days later I took my husband in to upgrade his phone to the s23 ultra. I am being told that because I shut a line down when I took my son in and added him to my plan with a new number, that voided the trade-in credit. But my husband has been receiving his trade in credit. Which makes absolutely no sense. Even the store manager said if they were giving me trade-in credit on one phone they should be giving me trade in credit on the other phone. So I called loyalty like the store manager advised me to do, and after being on the phone for 2 hours with loyalty their excuse for me not getting the trading credit was that they sent me a text message stating that I shut a line down and would lose my promotional credit if I didn't call customer service. Yup, I shut down a line but ADDED a line immediately. I never received that text message. Had I received that text message I would have went straight to the store and gotten it taken care of. When I asked for proof that they sent me said text message, of course I got the runaround. When I asked for proof that they had a read receipt that I read the text message, of course I got the runaround. The call ended with me very irate. It's been 3 years and potentially $2,400 that I've been screwed out of with this company. I am paying off my phones and I am leaving. I've already contacted a lawyer in regard to a (Edited per community guidelines) (Edited per community guidelines) because it seems that a lot of people have this issue. And when I say a lot I mean thousands. And what really gets me is that when I cancel my service I lose my trade in credit for my husband's phone. So they get to keep the phone that I sent in, refurbish it and sell it and I don't get anything. Can you imagine how many people this is done to? And how many millions of dollars this company makes off of that?