I was in the same.position as you UNTIL BBL mobile App suddenly would not work on my "old" phone operating system. It now requires android 10 or above.
(Yes, can buy a new phone!)
** had been using this mobile number for about 15yrs, so known to many people and agencies (Immigration ,hospitals, airlines etc)
So, in the interim , I decided to 'install' BBL Internet banking (iBanking) and use that.....
The sim card /billing was all still in my wife's name.
So very nice BBL staff pointed.out that due to the new law, the sim card (and same number) must be in my name (as per my bank acc) or no go with the mobile app OR ibanking !
I did ask,pointlessly, why I had not recieved any notification to this effect from the bank?
Shrugged shoulders !
Luckily AIS shop is opposite this BBL Branch in Future Park.
So over I go.
After a long time they came up with a plan to clear any outstanding bill to that date, and pay them B100.
BUT, then the new bill would not show my name until the next billing cycle!
Finally it was agreed.that they (AIS)would issue the B100 receipt in my name and showing the original mobile sim card number.
Back over to BBL (no new queue number or waiting) who were satisfied and corrected their records and set up the ibanking!
All in all about 4hrs+ to complete.
Be warned!!!