I recently tried this method with Bangkok Bank. I had to use my home bank to order the 12 month statement. I had to come back a week later to pick up the paperwork to include a statement from the bank itself. You need plenty of time.Cost was approx 500 baht or thereabouts
Bangkok bank has clamped down on agents putting in 800,000 baht and taking it out again within minutes. A lot of agents asking for customers to use different banks. Best to confirm with your agent. Or if you have made 12 or over regular monthly deposits each of 65,000 baht you can use that method