Won’t send return label for incorrect phone

I went to Xfinity over 2 weeks ago to upgrade my phone. The employee ended up ordering the wrong gigabyte iPhone and they told me the only way to exchange it for the correct one was to activate it, and when the new one came they would activate that one and I could send the incorrect one back. Well sure enough when I click on the return label in my email, it said “Page Not Found” on the fedex website. I have called over 4 times and spent countless hours wasted on the phone just for every single representative tell me it’s “grayed out” and they can’t send me a shipping label. They can’t even give me an address of where to send it. How is it possibly in a huge company like Xfinity that one single person isn’t authorized to send a return shipping label for a phone they can see in my account, that has a receipt and an exchange number?! That they ordered incorrectly in the first place? Is this a scam?! It seems impossible and I am beyond aggravated and ready to switch back to my old carrier.