Cant make calls or text. Under sim card says unknown number

Issues making calls and text. Recently switch to Xfinity mobile and right away had issues.  Support chat has tried troubleshooting this with multiple time but couldn't fix it.  They advised me to go in person to a store to help troubleshoot more.  I went in person and for 2 hours they troubleshoot it and couldn't fix this. It has a PSim card now but still not working. They said my only options were to take it to a repair shot to fix it, which i dont see why because it worked perfectly fine with a Psim card before i switched to Xfinity or to upgrade to a new phone. 

Device- Samsung S21 5g