trade in device issue

I purchased a new phone through Xfinity and received an email with th shipping label. When I attempt to open the label I am unable to open it ans get an error saying it has been coded incorrectly. I have spent hours on a chat and then was told to call customer service. I called customer service and my call was disconnected and I received a text with a link to xfinity chat. I have finally gotten a call back from a representative that is very nice, but has no idea how to help me (I was given the xfinity link as a link to the tracking label and then told to type in some random numbers into my phone to generate a label- you can't make this stuff up). It appears that Xfinity does not honor their trade ins anyways as there are multiple complaints about not getting the check. Has anyone successfully traded in a device?