IVETTE FELICIANO:

She says her host family never paid her for those extra hours.

Among other things, the suit filed in 2014 alleges that:

You can't legally deduct 40% from the minimum wage for room and board if the program requires au pairs to live with families, which it does.

That agencies colluded to keep au pair wages low. An allegation they deny.

And that at least four of the agencies violated federal labor rules that say families must pay their state's minimum wage if it is higher than the federal minimum wage.

A spokesperson for one of the agencies, Cultural Care Au Pair, disputes that contention. He sent PBS Newshour Weekend the most recent State Department notice regarding stipends, which is from 2007. He says the State Department has never told the sponsor agencies that employers must meet state minimum wage requirements. The State Department, however, told Newshour Weekend sponsors must adhere to state and local laws.

Among other things, the plaintiffs' attorneys are asking for what they say are unpaid wages and the return of illegal deductions. They estimate total damages at more than $2.5 billion.

PBS NewsHour Weekend reached out to all 15 of the 16 agencies named in the suit, but none were willing to speak to us in an interview.