if u stay in BKK, go to Bangkok Bank head office in Silom where they will open your account with just a tourist visa. Some branches will but others won't.
u can get the bank letter at least a day before. For the bank book u can update it yourself on the machine outside the bank. I had also updated my bank book day before and it was ok
at CW, u go to your bank downstairs and get a letter to show your 800k. And they will update your bank book at the same time. Take less than 30 mins at bangkok bank and letter is 100B. Then go upstairs to get extend your visa at Immigration. What so hard ?
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