Byline: Barbara Wall

AFTER returning from vacation, you discover that you have been the victim of a card fraudster. You immediately contact your bank to sort out the problem. But will the bank believe that you were not the one who ran up the unexpected debts?

Proving that you have been duped is not always straightforward. One particular fraud that is shockingly simple, and yet very difficult to corroborate, catches many vacationers unaware.

It works like this: A dishonest merchant makes multiple imprints of the customer's card and then uses these imprints to make a few other transactions, in addition to the genuine purchase. Since vacationers are the prime targets, and the sum of money involved is usually quite small, the merchants are rarely brought to justice.

Another trick, commonly practiced by rogue merchants and hoteliers, is to overcharge card-flexing customers for one-time-only purchases. If you are unfamiliar with the currency and have only glanced at the receipt, you may not spot the...