Xfinity mobile order not delivered

I ordered an iphone 11 pro max from xfinity on 12/04/2019 and it was supposed to deliver on 9th. On the delivery date I could not be at home and I thought Fedex might redeliver it on next day. But I received an email around 1pm the package was delivered and someone even signed for it. I came home to find a door tag in my home saying will try to deliver package to apartment office. When I went to the apratment office they said they didn't receive such package. I immediately contacted Fedex and their supervisor told it has been delivered to some man whom she even described appearance. I made a claim to Fedex they denied it saying that per their insurance policy,  xfinity has to make the claim. Then I called xfinity and made a claim and it was also denied with no apparent reason. I have been reaching to xfinity customer care for help, but every time they have one answer. "Your case was denied there is no reason on file. But it was denied, so its your liability to pay for the device" I have two questions to ask

1) Isn't xfinity orders supposed to be delivered to the address on cable service? So how come it be my liability when fedex deliver it to an office when no body is at home?

2) Why can't customer care/investigation team tell me why the claim was denied? Atleast customer should have the right to know what happened to the investigation.

To me it seems like both xfinity and fedex trying to save themselves and putting customers to trash.  I believe if it is fedex's fault xfinity should stand by their customers. And if you can't solve these type of situations, you should not shipping online orders in the first place.. Now I am paying $45.8 each month for a device I didn't receive.