there is something I don't understand here - in the Bualang app (Bangkok bank's mobile app) you can request a 12 month statement which is sent quickly by email. So that you were told only headquarter can do this I don't understand.
strange it should take so long - I recently went to immi Udon Thani - waited around 30 minutes then said I want a certificate of residence to open another bank account - waited around 20 minutes and got it (500 baht)