Most Thai banks will NOT open an account for someone that does NOT have a proper address and/or has less than a week remaining on their
*****
Day Visa Exemption stamp.
You NEED a Certificate of Residence from Immigration to open an account (normally - assuming you aren't using a shady agent).
As well - from MY experience - they will NOT open an account and grant "internet banking" to anyone without a actual Visa of some kind.
I had to have an Extension (1 year) of my Non-O Visa before Bangkok Bank would let me use their iBank system.
But a friend of mine who was on a Double-Entry Tourist Visa was given access a couple years ago (same bank, different branch).
And if YOU tried the old scam of trying to open a Chequing Acct - forget it. They only open chequing accounts (or issue credit cards) to people with WORK Visas and WORK Permits.
Yeah, they are well aware what people in flip-flops, stained shorts and filthy "wife beater" t-shirts are trying to do when they ask to open a Chequing account and try to give the bank clerk 100 baht to deposit into the account a week before their 30 Day (back then) Visa Exemption stamp expires.
Used to be a lot of foreigners would try that and then go onto the forums and whine that (insert bank here) was prejudiced against (insert your nationality here) because they wouldn't open an account for them.
And when you ask them what type of account they were trying to open - "the sounds of silence, broken only by a lone tumbleweed rolling past".
Because they won't admit what they were trying to do.
And MOST of the advice from the "old days" was - if you get turned down at one branch - simply go to a different branch - or different bank.
As each of them may have slightly different policies regarding opening accounts for foreigners.
As well - try going to a large branch in a touristy area - or a branch office inside a large shopping mall.
Because those branches are more likely to have more dealings with foreigners - and more staff that speak "your" language.