FedEx lost my trade in phone and Xfinity is trying to charge me bc they don't want to file a claim with FedEx

I have several open tickets, I have 3 way called FedEx and Assurant about where my phone is at. Xfinity has completely disregarded my problems. Now they tried to charge my card $500 for no reason. I need corporate to call me and either give me top dollar for my trade in or send me my phone back. 

It has been 3 months that I have been dealing with this everyday. No American customer service agents at all ever. 

They all just create these "tickets" and nothing happens. They refuse to let me talk to an actual manager. I am getting thieved from in all kinds of ways from Xfinity and FedEx but mostly Xfinity. I need someone to help this situation asap