I had mine just done with KTB and SCB all on the same day a
12 months statments, letter of guarantee the lot, afternoon at immigration all done by 3.30 in the afternoon, there were lots of people there, but very efficient, if copies are needed, they tell you, can get them done at the outside, and officer will wait for you until you return with the copies, Pathum Thani immigration very good, and always explain everything
no, before I left I got told that it is my responsibility to count the 90 days and just report to the office, which I done, no TM 30 or anything else been asked for besides my passport and copy of passport
a letter of guarantee from the bank, that this money is in the bank account, and bank book. The cost is usually around 200 Baht. Then you should have no problem.bankbook alone is usually not good enough