When shopping overseas, I have been asked whether I wanted to be charged in the local currency or in Singapore dollars.

I used to think it made sense to use the Singdollar.

After a few such transactions, I checked to see what I was actually being charged.

To my surprise, I found that the rate used to convert the cost to the Singdollar was exorbitant; I ended up being charged far more than if I had used the local currency.

Upon further investigation, I found this in the small print of charge slips: "This service is offered by the merchant's service provider, with FX rate at Visa rate plus four pt. nine nine (sic) per cent."

I do not know why 4.99 per cent was written in text rather than figures. Perhaps it is to make it not stand out when customers glance quickly at the terms.

Now, knowing that paying in Singdollars incurs an additional cost of nearly 5 per cent, I no longer accept being charged in this currency.

I suspect that a similar tactic is being used with the reported overseas transaction fee (Overseas transaction fee charged for some online buys; May 27).

We consumers should hold credit card companies to a higher level of accountability for allowing middleman merchants to conduct such a practice.

Lim Chiew Sen