I have NO SERVICE and/or SEARCHING

A couple of weeks, a day after I did a software update i started having no service. Things i've done:

-Went to t mobile and they check sim and network settings and the said those were fine.

-I swapped sim cards my self and it still didnt work.

-Called apple support and after a whole day of BS from them they said I need to go to apple store. ( Apple store is 150 miles away and I havent had time)

- Reset Network settings myself and nothing.

Reset iphone a couple of times and everytime i do that the phones service comes back up for a few hours and then its gone.