[Dan]

If you have the POSB account, goto the POSB account and click Request Change Oversea Transfer Limit. Change it to a very low amount.

Why set limit to minimum when you're in S'pore? Set it to zero. If say you need 300 for a certain purchase reset it to 300 and back to zero after the transaction. POSB don't charge you any fee even if you reset it a few hundred times.