They often come to a shop, buy a phone card and then ask for a refund by 'returning' the card. The trick they usually apply is that they return a finely-packed used card instead of the card they purchased from the retailer.

Several card retailers in the city alleged that they were deceived by the cheats on several occasions in recent months.

They said when the well dressed frauds come to their shops to buy cards, the salesmen do their best to treat them rightly as customers. There is nothing to be suspicious as the 'customer' pays for the card and leaves the shops.

But, within a few minutes, the customer returns asking for a refund saying that he has enough credit in his cellphone. As the card inside the poly-pack seems fine to the salesman, he refunds for it to the customer who walks out of the shop.

While selling the same card to another customer sometime later, the salesman, to his dismay, finds the card a used one, said Mohammad Ali, owner of a phone-fax shop at Kalabagan. Ali has already been the victim of such fraudulence.

The frauds sometimes buy several cards at a time and deceive the salesmen by 'returning' one or two cards a few minutes later in the same way.

"These incidents happen regularly at shops having new hands or inexperienced staff," said Gobindo, a salesman of Azad Watch Shop in Moghbazar.

The pre-paid card sellers earn a fixed commission -- Tk 1.5 for a Tk 50 card, Tk 9 for a Tk 300 card and Tk 18 for a Tk 600 card.

On the other hand, innocent customers may fall prey to these situations as well.

There have been numerous instances where customers bought a card, went home and found that the card did not have any credit. In that case the customers do not get their money refunded from the shops.

Most retailers ask the customer to refill their account before leaving the shop or in presence of the salesman. The operators have also requested the retailers to receive supply of cards from only the authorised agents.

"In case of flawed cards, a customer should complain to the customer support department of the company concerned and provide them with the card's serial number," said a customer relations officer of a leading cellphone operator.