exactly what happened to me 24 yrs ago! Had to employ agent who managed to cut the tax request by 50,000 baht! Nightmare but back then not much Google advise!
for an agent setting up everything if you don't apply for O Visa that is about the current charge. Get O visa, open bank account yourself and visa cost 1900 baht
nothing to do with banking! It's low season same every year, its quieter than some September in the past as many Chinese now go to Japan. Expats are angry and so they should be, but only Bangkok bank will suffer long term from them