Their representatives urged the Consumer Protection Board to investigate the Small and Medium Enterprise Development Bank of Thailand (SME Bank) and a private company involved in the sale of the equipment.

They claim that SME Bank advertising lured each of them into buying three pieces of equipment - a TV monitor, a credit-card machine and a GPRS receiver - from the company via a loan of Bt60,300, including interest.

Rasamee Vistaveth, secretary-general of the Consumer Protection Board, received their complaint.

The cabbies' taxis were bought in 2003 on hire-purchase contracts under a government initiative to allow taxi drivers to own their own vehicles.

"The bank advertised so many good things about the equipment," said Suttisan Kotchasenee, one of the complainants.

"We were told about their many benefits when we had a meeting with the representatives from the SME Bank and the company," said Sompong Chomkamsing, who represented the taxi owners.

He said the drivers were told they would earn Bt500-Bt850 a month as fees for ads shown on the monitors. They were also told that they would earn Bt5 each time a passenger charged a fare to their credit card. The receivers were said to help them find passengers.

After installing the equipment, they found the items were of no benefit to them.  "We never earned any extra fees from the equipment," Sompong said.

Under the terms of the deal, the drivers have had to pay Bt1,005 in monthly instalments over five years. The principal was Bt46,000, rising to Bt60,300 after interest.

 Sompong added that the company that installed the equipment had refused to take back any of the items, while the SME Bank had refused to make public details of the contract with the company.

Rasamee said her agency would listen to each driver to determine exactly what they had been told about the equipment. "Then we will invite representatives from the SME Bank and the company as well as the complainants to meet and explain their stance in the next two weeks," she said.