Bad customer care

I have been trying to get a phone back that was shipped to T-Mobile by mistake. It was supposed to be shipped to Samsung. I was told that the phone was in the warehouse and I would receive it in 10 days. I called to follow-up, I was told that it was my thought and I could not get the phone back. I wrote a letter to corporate A few days later, I received a phone call early morning telling me to go to a phone store and they will help me with the issue. I go to a phone store. They called customer care and gave me the phone I was on the phone on hold for 45 minutes. I was told that I would get the phone back in 10 days. I still have not received the phone. I called to follow-up again. I was told the same thing I would get the phone back in 10 days. It was in the warehouse. I still have not received the phone. Samsung has charged me nine hundred dollars for that trade in phone, but I was told once I get the phone back from t mobile and ship it to them.They would refund me my nine hundred dollars. I have been a T-Mobile customer for over 15 years. And this treatment, it's very unacceptable. I pay my bill every month. Never late, I have 5 lines. With T-Mobile, I have 2 Galaxy watches, 1apple watch 4 trackers and 2 tablets. I pay over $500 a month. And this is the kind of treatment that I get. Your help will truly be appreciated