Received the notification as well today. Turns out that if you renewed your passport at some point after registering with either your bank or a mobile services provider, you need to update your info with both. My bank account was updated with the new passport number a few years ago because you need to show it everytime you visit for immigration purposes or tiny little changes to your account. But AIS or True or DTAC? I never need to see them, I do everything I need on my app, hence I never updated my passport info with them. It wasn't asked or required.
The thing is, this crossreferencing system by the government to avoid scamming/abuse/cybercrime and to track users was made for Thai nationals, who use a permanent, National ID Card number that never expires. For foreigners, the info they rely on is passport info.
So, if you renew your passport at some point and fail to update both your bank and your mobile service provider, the crossreference will produce a missmatch and will trigger the account freezing notification.
So tomorrow I need to go to AIS, update my passport info, get the letter, and go to the Bank. And when I get a new passport in 7 years, I'll have to update both my bank and my mobile service provider again, as I guess they will do these kind of crossreference between Bank Data and Mobile Phone Data every 6-12 months to root out the possibly fake/scam accounts.
Ideally, long term expats here would get a permanent ID number that would never expire, and we would avoid this kind of issues. We can't blame the banks or the mobile service providers, this was asked of them by the government. And the government doesn't care about non-Thai nationals, it's their problem to fix. At least, that seems to be the mentality.
Perhaps, in the future, Thai government will start issuing some permanent ID with a permanent number for non-Thai nationals, and this number will be used for this kind of stuff, just like Vietnam is doing right now. But at the moment, we're stuck in this imperfect system.
The most annoying thing is that the info we got some months ago was that the NAME had to match in both the Bank and the Mobile service account. They never mentionned the Passport info. I even called Bangkok Bank 3-4 months ago to make sure I wouldn't get flagged, and the lady told me : "As long as your name is spelled the same way and matches in both accounts, you're good to go". I think most of the staff didn't even know about the Passport number having to match. Poor communication, poor transparency from the government doesn't help in this case, obviously.
, you really removed a lot of stress on my mind, and I am eternally grateful for your help. It's not the first time, and probably not the last. Thank you so much for your precious advice! I will pay it forward!
That's pretty clear, thanks for confirming what other posters mentioned in an extremely clear way! (I mean you are being extremely clear, I'm not being sarcastic!)