Can't set up cellular on apple watch

My son’s apple watch number is under my account, it is a standalone smartwatch plan(falimy set up).

After I reset the watch, just can’t set up the cellular back.

When I check my Bell account, the device imformation is still under that number,

Is it because the watch IMEI still paired to the esim, how can I remove/unpair, so that I can reconnect again?

I have called several times, have not solve the problem yet. The only way is wait for them to call back???

hit up Bell’s tech support and tell 'em to give you a call back. Drop your current watch plan (sadly, you’ll lose the old watch number), but then set up a fresh watch line with a new number. It’s a quick one-minute fix, but believe me, it took me more than a week and over 10 calls just to get here! How’s that even possible? I asked regular customer service if this move could solve my issue, and they said, “No way.” But guess what? Tech support hooked me up the exact way customer service said wouldn’t work. Go figure!