I went to the Bangkok Bank at Central Rama 9 to get the bank letter for my non-o marriage extension, and they didn't understand my request. They said they could only give me a statement, but not a letter. Is there any reason not to just get it from the branch in Chiang Wattana on the day I go in for the extension instead of getting it in advance? I assume that I should have time to do that before they get to my queue number.