I gave up trying to solve this at the mobile operator level, they don't care, they don't get fined/sued enough and legislators are too incompetent/slow to fix this.

I just never use any service that forces 2FA by SMS. If it not avoidable for some reason, I make this account completely isolated from the rest of my online identity (new email just for it, regularly change password).

If your bank/financial institution forces 2FA by SMS, it is time to change, most of the serious ones have their own app that handles 2FA. I'm yet to find one that allows to use your own OTP generators, so I'm usually forced to use their app for now.