Wing shing can pay cc without additional surcharge. Bare in mind you will loose typically 4% savings due to the infavorable exchnage rate by CC versus what you change in Sgp.
As a real example, the rates I change in early dec is 1SGD=5.33HKD but credit card used 1SGD=5.23SGD
Use cc only if you really have no choice else the 3-5% diff can buy you a good meal!
NOTE: no point changing to HKD in HK as the rates there worst than cc.