As of yesterday SCB ATM (Mega Bang Na) with MasterCard is 220 THB.
As of last week, AEON was (still) 150 THB using Visa.
My best guess is that there is a current transition from 200 to 220 using MC.
http://www.thaivisa.com/forum/topic/...s-to-220-baht/
CitiBank (incl. international presences like Australia) may offer fee-free/reimbursed ATM withdrawals. But there are only a few locations in Bangkok (Central World, Asoke among two I know of).