Never Received Device

Hello,

I recently ordered an iPhone 11 pro max and never received the device. FedEx has denied the claim and I am irate! In addition, Xfinity is stating there is nothing they can do about it and have charged my account almost $700 for a device I never received.  Xfinity also claimed they were unable to provide me any proof of the investigation nor facts as to how Fedex came to the conclusion to deny my cIaim. I believe this is unfair and I am out of 700 bucks for a device I never received. PLEASE HELP!