Xfinity Mobile is so frustrating! I am about to have my $250 prepaid card and I asked the CSR to have it send to my residential address using FedEx or UPS with signature requirement. And they just won't! For a $250 Prepaid card, they will use USPS with no tracking and no signature required!!! That is unacceptable!
When I asked if I could have a mailing address, they told me they must send it to my residential (where USPS is the worst, and I haven't been receiving mails via USPS for a month)! I'm so disappointed! Guess they don't care if the $250 prepaid card is lost or not. If that is the case, and if my $250 should be lost, I guess I will complain through BBB then.
I am not sure your concern is with Comcast. It sounds like you have an issue with USPS. I would recommend contact them instead of filing a complaint with Comcast. Comcast does not control USPS and if they have a policy that they have to send it to you via USPS to your home/service address, there is not much the BBB can do to assist. A simple Google search will provide you with the contact info for USPS and a place to report your concerns about not receiving your mail.