I could not even put in my Thai telephone number in my bank apps (Bangkok- and Kasikorn bank) in international format (with + country code and leaving out the zero). I really don't know but maybe, maybe a vpn works 🤷♂️ I would say try and maybe let us know. Good luck.
I'm retired and have a credit/master card. You get it when you follow their procedure. Before I tried with 4 banks and they did not refuse immediately so had to fill 15-plus forms they would send to the main branch in Bangkok. With all 4 banks, I got an SMS within 2 weeks that it was refused due to bank policy. Then I went to a Kaskorn branch in Korat and said that I read that if you open a Fixed deposit account, as some kind of collateral, I could get a master card. They confimed, opened the fixed account, I put money in it and fill the forms to get the mastercard. Within 2 weeks it was in my mailbox.
I'm retired and have a credit/master card. You get it when you follow their procedure. Before I tried with 4 banks and they did not refuse immediately so had to fill 15-plus forms they would send to the main branch in Bangkok. With all 4 banks, I got an SMS within 2 weeks that it was refused due to bank policy. Then I went to a Kaskorn branch in Korat and said that I read that if you open a Fixed deposit account, as some kind of collateral, I could get a master card. They confimed, opened the fixed account, I put money in it and fill the forms to get the mastercard. Within 2 weeks it was in my mailbox.
The nonsense worked for me. But I think basicalley you are right with 'Fixed' account. What happens is that if I pay e.g. 2,000฿ with my mastercard, it's deducted from my xxxk฿ on my fixed deposit account. Strange indeed but that's what happens. Then within a couple of days, I have to 'pay the bill'. When I push that button within the app, the 2,000฿ (in my example) is transfered from my savings account to that fixed account and the limit is again like before. By the way, I get interest every half year. Same like the savings account.
I read before that there are different 'Fixed deposit accounts' like Kai Kwan mentions. I asked if I could redraw the whole amount of my Fixed account when I wanted and the answer was yes. But.......You lose the interest from the last half year and y'r Mastercard.
Oh, sorry to hear. There are 2 kind of agents/agencies if you know what I mean. There is no problem using one if you can fulfill all requirements you need for y'r imm. Better go for the legal path, otherwise in future you can run into problems. Good luck !