One Romanian couple were jobless until they saw a Xawax ad on Facebook this summer.

The couple, ages 23 and 24, said a recruiter had promised free lodging, regular shifts and wages on par with Czech factory workers — at least €585 a month — better than what they could get in Romania. They boarded a bus packed with other recruits bound for Pardubice. There, they signed a six-month employment contract with Xawax that was written in Czech, a language they couldn’t comprehend, without a translator present.

At 5:30 the next morning, they were transported to the Panasonic factory to join more than a hundred laborers in a cavernous hall assembling electronic components. The couple said Xawax had soon told them that they would have to frequently work overtime or receive bonuses just to get their promised wage. The terms were included in the contract they could not understand. After the woman got sick at work and fainted one evening, requiring her to be rushed to a hospital, she received little help from the agency in organizing follow-up treatment, she said.

Katerina Kotrla, the director of a nongovernmental organization that helps migrants in Pardubice, said such workers tended to be more easily exploited and had little recourse. Ms. Kotrla has handled numerous cases in which agencies, including Xawax, stayed within the law but provided inadequate health care assistance, cut pay when injuries prevented people from working or didn’t pay overtime.

“The agencies have a lot of power over these people,” she said.

Jan Hendrych, the chief executive of Wincott People Group, one of Eastern Europe’s largest employment agencies, which acquired Xawax this year, said his company followed the labor laws of all countries where it hired workers and was unaware of such practices. But if an internal inquiry showed Xawax had engaged in them, he said, “that kind of behavior is obviously unethical at the very least, and must be stopped.” He added that Wincott had worked with the Czech government on measures to clean up irregular agency practices, which would help attract workers.

In a statement, Foxconn Technology Group said it and the agencies that recruited on its behalf had ensured workers received wages and benefits above the Czech Republic’s basic requirements. Foxconn added that its operations were regularly audited, and that it complied with relevant local laws and regulations.