The District’s effort to modernize its taxi fleet has hit another snag: Some drivers say they are not receiving thousands of dollars in fares paid by credit card.

“It’s been 15 days,” said driver Fakadu Bebane, a father of four, who estimates that he is owed more than $1,500. “They say the money is coming but . . .

For drivers, this development is another in a series of frustrations cabbies said they’ve encountered as the District has moved to make its taxi fleet easier to use and more competitive with car services that have begun vying for passengers. Drivers say the new requirements, which include the installation of credit card readers, larger and brighter dome lights, and a new red-and-gray color scheme, are too costly and coming too quickly.

This month, five drivers filed suit in U.S. District Court for the District of Columbia, asking a judge to block implementation of the new rules — the most expansive overhaul of the city’s fleet in nearly three decades. Among their arguments, the drivers contend that the new regulations violate the Americans With Disabilities Act and discriminate against older drivers in part because the new dome lights require drivers to get out of the vehicle to operate them. Such actions, the suit contends, are a physical burden on older or disabled drivers. They also argue that new GPS trackers are an invasion of driver and passenger privacy.

“They try to portray us as being against modernization, but we’re not,” said driver Ahmed Djebbour, one of the five who sued. “It’s just total chaos.”

In a response to the suit, District officials say that none of the drivers involved in the lawsuit are disabled and therefore lack standing to sue. The city’s lawyers also say there is no violation of driver or passenger privacy because the GPS tracker has safeguards to ensure anonymity.

Temporarily halting implementation of the rules would burden the drivers who have complied, city officials say.

Ron Linton, chairman of the D.C. Taxicab Commission, said that although he could not comment on the lawsuit, he has been surprised by the outcry from cabbies. The regulations, which were two years in the making, should not come as a surprise to drivers, he said.

“They’re really resisting against their own best interests,” he said.

Meanwhile, officials at Hitch, the payment processing company that the affected drivers use, say they are working as quickly as possible to resolve the credit card payment issue. But they maintain that the problems aren’t entirely their fault. David H. Miller, Hitch’s chief executive, said that in some cases, payments have been delayed because the company received bad information from drivers, including inaccurate bank account information or routing numbers.

‘This will all shake out’

The District-based start-up, which serves about 1,600 of the estimated 6,100 D.C. cabs that have installed the new readers, is one of eight companies cabdrivers may contract with to handle credit cards. Customers swipe their cards through a machine, and Hitch routes those payments to the drivers after deducting a service fee and the 25-cent surcharge that goes to the cab commission.

Miller said the company has made changes, such as requiring drivers to submit a canceled check to ensure that the company has accurate bank information, in hopes of preventing future delays in payment. The company also has an assistance line and has established hours for its employees to be stationed at various cab companies to help drivers address issues.

“We believe this will all shake out in the next week or two,” Miller said.

Cab commission officials said they are aware of the problems and are working closely with Hitch and the drivers to resolve the payment issue and other technical problems the company must fix as part of its agreement with the city. Last month, the commission and company officials reached an agreement that allowed Hitch to continue operating as it worked to remedy the problems. Miller, however, maintained that all issues had been resolved.

Still, it is small consolation to cabbies who say they depend on a regular flow of fares to buy groceries, pay rent and cover other expenses.

“They’re not getting paid on time,” said Mo Rahim, who runs the 250-car Rock Creek Cab. “There’s a lot of confusion, and cabdrivers have to bear the worst of it. ”

‘We always have trouble’

Indeed, late last week, drivers made their way to Rahim’s shop on Franklin Street in Northeast Washington to see what could be done about their payment problems. Rahim said he knew of at least one driver who was waiting to receive $3,600 in fares paid by credit card.

Cesar Beltethon, who drives for Rock Creek Cab, said he had to wait several weeks to receive $1,000 in fares. He has since been paid but remains uneasy.

“Trouble,” said Beltethon, who has driven a cab for more than 20 years. “We always have trouble.”

Commission officials said exact figures for the percentage of fares paid by credit card are not yet available, but in the first year of operation, officials projected that about 20 percent of the fares would be paid by credit card, according to Neville Waters, commission spokesman.

The new credit card readers vary in price, with some units costing as much as $400, and come with monthly fees. The new dome lights, which feature a digital display, can run from $180 to $500. Waters, the cab commission spokesman, said a 25-cent surcharge has been added to all fares to help drivers pay for the equipment.

‘Everything is coming in’

As part of the city’s push to modernize the system, drivers were required to have credit card machines installed in their cabs, but the process proved to be more complicated than officials anticipated. Even though Mayor Vincent C. Gray (D) said the new system would be ready by summer, the August deadline had to be changed to the end of September because of equipment shortages and issues with installation.

Waters said that according to the most recent numbers, 91 percent of the District’s 6,500 taxis have the readers installed. Drivers who haven’t met the deadline risk having their cars impounded.

Some drivers said that after initial hiccups, the Hitch processing system has made their lives easier, customers happier and their tips bigger.

“I was worried about getting the money on time,” driver Charlie Kim said. “But now after two to three days, everything is coming in.”