5c says no service, help?

For the past 3 days my 5c has said no service for almost every second of the day. It'll sometimes say no SIM card and then briefly give me service before going back to no service. It's not my provider as they've assured me there's no problem with the tower. I've tried everything I know and have read, reset network settings remove SIM card, cleaned SIM card etc. Only thing I haven't done is a factory reset and go to an Apple store. Anyone been here and know a fix? This is my only phone and need it. Apple support hasn't helped because the insist on calling and obviously I cant do that. Any help would be great.