I have this constant issue where my signal suddenly goes and says sim card refreshing happens afew times a day now. I recently orderd a new sim card. Still does it, really like the 48 deal but if this is regular occurrence I'll think just jump ship.
Ive Samsung Galaxy 10 btw
Seems to be a common problem with some Samsung Galaxy phones on 48 and lots of other networks worldwide unfortunately.
Just search for "Samsung Galaxy refreshing SIM data" and you'll see.
Maybe try the Samsung support forums but I've never seen a fail-safe solution myself.