Network not registered or cannot connect to the network

Samsung Galaxy 15a 5g. Ordered on the 20th of February activated on the 24th.I ordered one for me and one for my husband. I continuously get the error not registered to the network or cannot connect to the internet with the secondary message emergency calls only. On February 27th I went to the store and they put a new sim in it. Still having the problem. Whenever I reach out to xfinity they want to trouble shoot.  I visited the store on the 11th of March the store finally said we've done all we can. File a claim with Assurant. After today trying to make a call and getting not registered to a network. Emergency calls only. Restarting my phone is the only way to fix it I reached the breaking point.  I tried to file a claim.  My problem does not qualify for a claim and I was told to call Xfinity mobile.  At my wit's end I reached out to xfinity. I was on the phone for an hour. The rep talked to her supervisor and told me they were going to replace it and I would get a confirmation email within 2-3 hours. I never received an email.  Call back to xfinity and on the phone for 3 hours!! I guess I was lied to because no record of replacement phone. The rep filed an escalation ticket (yes I have a ticket number). He says it will be resolved in 24 hours.  Do I believe that? NO!! The rep felt so bad for my experience with xfinity that he gave me a $60 credit. My husband has no issues with his phone.  Only I have the problem.  My phone is 22 days old! I need help!! Like NOW