Returning wrong color phone

I went to the Xfinity store on 6/29 to do two things. First, I wanted to change from My Verizon cell to the Xfinity premium cell line to receive a promo discount on a years worth of service. Once I did this, I could upgrade my iPhone 13 Pro 256 GB Natural titanium to an iPhone 16 Pro 256 GB Natural titanium. Because the store did not have one in stock they placed an order for me and the phone was delivered today By FedEx and I signed for it. When I open the phone, I saw that it was the wrong color they had sent a desert titanium, and I wanted a natural titanium. I thought this could be easily fixed by just returning the phone to the center that sent it and have them send me out a new phone . I called Xfinity support. They told me I had to activate my new phone before they could return it.  So they wanted me to activate my new phone, then deactivate my new phone to get so I would have my phone to use when I sent the new  phone back in. They also told me that they couldn’t guarantee the same promo value for my Trade-in at this time?? I don’t get it. What’s the deal? They’re the ones that made the mistake. I should be able to get a label to return this phone and hopefully have the center return the correct phone with the correct color. Why do I have to activate? And why does the promo now not exist?