I am getting the run around trying to get my cellphone service restored.Please Help!!!

My issue started two weeks ago, all of a sudden my cellphone service stopped working it would come in and out, and most of the time the icon on top would be a circle with a line across it. I called  Xfinity, they had me reset my network settings and then restart the phone which worked but worked for about 20 minutes then I had to call back on another phone letting them know that it happened again. The guy recommended that I go to an Xfinity store and replace my sim card so I go and do that and it works. I get to my car and drive off and once again my service is gone. I call Xfinity again and tell them what happened so they transfer me to the Advanced Care Team they have me reset my network settings and restart my phone I tell them I have already done this and the guy says he will open a ticket with Verizon so a technician can check my network. He said it will take a few days which happened on a Friday. I call back on Monday afternoon and they still don't have an update. So I call back the next day and I ask for the advanced care team and they say they are doing things on their end and I am just on the phone waiting they ask questions about the phone the IMEI number and the Sim card number and I tell him whatever you guys do it only works for about 20min and then my phone loses network. So after almost two hours on the phone, nothing really gets accomplished. I call back again the next day they said that Verizon technician doesn't see anything wrong on their end and neither does Xfinity so they recommend that I open a claim with Assurant to get a new phone it takes a few days and I get the phone I take my sim card out of the old phone and put it in the new one and it works for about 10min I call them again the guy gets my cellphone info again and they determine that the phone that was sent to me by Assurant had been reported stolen the guy on the phone said give him a couple of days to resolve this mess. I hang up and an hour later I get an email from Xfinity saying my line has been canceled and to call them immediately if I did not cancel my line. It was already too late to call so I called the next morning and they reactivated my line but it would 24 hours for it to take effect. My got reactivated today and I still have no service on my phone I was on the phone with Xfinity again this afternoon they said that the reason it wasn't working was because I was using my old sim card and to use the one that came in the box. So I give him the number on the new sim card and he said he wasn't able to activate it and would have the Advanced Care team take a look at it since they have the tools to help and he doesn't. So they make the change on the network and he said would call me later tonight so I eat dinner and watch some tv he said he would call me about an hour and a half later, he doesn't and I call back with the ticket number he gave me and the lady said that the Advanced Care Team is still processing it and that she couldn't anything since they have the tools to do it. So she says to call back tomorrow since they are closed and can't transfer me to them. I am just done with this. I am about to cancel my mobile service because this is ridiculous. I have had service with you guys for a long time, I have never had issues with your Internet service but your mobile service is bad. I hope someone can help otherwise I will just take my business elsewhere.