Charged for phone I returned!

So I took I promotion to exchange my s23 ultra for a s24. Phone was too big. Anyways I had a Crack on my screen and had to use my insurance, so I could exchange my s23 ultra for a new one so I could trade in the crack-free one, so I could upgrade to the s24. I exchange and ship back old s23ultra and get my new one. that's taken care of. now I get my s24 and my wife ships the crack-free s23ultra. Before this, I tried returning to my local store ( groton, ct). they tell me they won't take it, I have to ship. I confirm the shipping labele emailed to me, they say yup send it there. Feb 23 @ 1pm my wife texted saying she went inside post office and shipped. I get an email a wk later saying I need to ship my phone, I call they say they have received it. OK, no worries. it shows up on my app saying I owe 766, phone bill is roughly 150.... great, so I called, they assure me they have phone ( xfinity customer care) and the bill showing would be changed and not reflect on my next statement. idk, maybe another week goes by, no changes but I wake up to no cell phone service right bf work at 4am. I call customer service on wife's phone, I confirm info and hand phone over to wife. they figure it out and she asks about charge, AGAIN. she tells my wife same thing. Fast forward I call the first bc I have over 600 dollars missing from my account. now they say they can't find phone. they need tracking. this is where I'm an idiot... I can't find it. since then we've tried post office, customer service, we're every 30 min I get someone new and start the whole process over. I sent over a month ago. I did my part, I was told I was good. I'm sorry I lost a tracking # but I was told I was good. so I never really thought to save it. it's a bigger mess and I just want my money back. I've been a customer for 5 yrs. never paid a bill late, got them 3 family members, 2 friends. I use to praise them. At this point unless they make it right soon, I'll return my cable boxes and get a new provider. as soon as my phone is within pay off, I will do the same. I understand they're trying to find the phone, but that's not my problem. I returned it and now am getting charged for it. this is so wrong. truly disappointed. Wish they would resolve it. That wasn't there money to take, also tried to shut off auto pay and wouldn't work. Xfinity make this right. has anybody else been here? what can I do? I've put so much time in already, I feel defeated.