When an airline bumps us from a flight or delays us for hours on end, most of us accept our meager meal vouchers and swallow our pride. A bold few might actually file a claim for compensation, but when an airline either fails to answer the claim or rejects it outright, those passengers usually give up, too.

Not Henrik Zillmer. When Zillmer had airline trouble a few years back, he "didn't take no for an answer." Instead, he pored over national and international flight regulations and scoured legal judgments against the airlines. What he found was that, in most cases, passengers who take their meal vouchers and walk away may actually be legally entitled to hundreds of dollars in compensation from the airlines. He crunched publicly available data on the number of delayed flights and the number of passengers per flight, and discovered that airlines collectively owe compensation to some 26 million passengers every year. The problem is that they're only paying about 0.06 percent of what they owe.

Zillmer, a serial entrepreneur, didn't just go after his own compensation. He set out to help all 26 million of those passengers. In 2013, along with Nicolas Michaelsen and Greg Roodt, he founded AirHelp, a company that helps anyone get paid when airlines mess up. The company now has 20,000 customers and counting, and it has won them millions in compensation in just a year of operations. When customers get paid, AirHelp takes a 25 percent cut. It's a business model that Zillmer calls "justice as a service."

>When customers get paid, AirHelp takes a 25 percent cut. It's a business model that Zillmer calls 'justice as a service.'

That might sound a bit self-serving, but AirHelp is one of a growing number of startups building businesses that help fight consumer battles. Fixed, a San Francisco-based startup, will fight to get your parking ticket dismissed and charge 25 percent of the fine if you win. Another startup, 71lbs, helps consumers get FedEX and UPS refunds if their packages are late and takes a 50 percent cut of the money won. "You could say it’s a logical next step in the whole empowerment of consumers. With social media, they could harm a brand," says Michaelsen. "Now, they're actually able to assert their rights and not just on a brand level."

The problem with this business model is that consumers could, in theory, fight these battles themselves – without sacrificing any of their winnings. But, Zillmer says, AirHelp increases your odds. "There's a much higher likelihood of you getting money using someone like us, instead of applying for compensation yourself."

That's because AirHelp's underlying technology aggregates massive amounts of flight data and checks it against national, international, and regional laws, as well as court judgments. That way, when a customer enters his flight number, date, airline, and route, the system automatically knows if he's entitled to compensation. Airlines aren't required to pay on delayed domestic flights, for instance, or if the delay was caused by an extreme condition, like weather or a security threat. But in nearly all other cases, they are.

The AirHelp system then generates a claim on behalf of the passenger and sends it off to the airline. If the airline complies, AirHelp collects the money and walks away. If the airline rejects the claim, AirHelp takes them to court. To date, the tiny startup has been involved in more than 20 court cases and has won nearly all of them. As AirHelp racks up wins in court, it continually sets precedents for future claims its customers will make. "Basically, we have to make sure they know we're not going to back off," Zillmer says. "We have to go all the way."

Not surprisingly, the airlines have been playing dirty. For instance, many of them require AirHelp to supply them with a signed power of attorney form for each and every client. When AirHelp customers realize they have to print, sign, and send the paper work to AirHelp, Zillmer admits, a certain percentage of customers never follow through (I know I didn't).

>'Basically, we have to make sure they know we're not going to back off. We have to go all the way.'

Other airlines demand an actual physical boarding pass to be presented, even though many people are now using mobile boarding passes, and the ones who aren't might well have thrown the physical boarding pass away. "They say otherwise they can't prove they were on the flight, which is complete bullshit," Zillmer says.

But AirHelp is pushing forward. The company is currently raising a round of funding, after completing a stint in Y Combinator in March. Meanwhile, at Tuesday's TechCrunch Disrupt conference in New York, Zillmer revealed a new tool that will automatically sift through your emails to figure out if any of your past flights from the last three years are eligible for compensation. It's just the first of many tools the company will be releasing, Zillmer says, to help make travel more convenient. In the future, for instance, he says AirHelp may hire its own airport concierge people to help customers file a claim or get booked on another flight while they're waiting in the airport. Filing claims is just a start.

Of course, if AirHelp really does its job in holding the airlines accountable, you could argue that would put AirHelp out of business. After all, if airlines started compensating consumers proactively, AirHelp's value would vanish. Killmer acknowledges this, but he doesn't think the airlines are going to be walking up and down the aisles handing out checks anytime soon. "They still call it a 'complaint,' not 'my rightful compensation because you fucking delayed me,'" he says. "As long as that happens, we’re going to be there."

Correction 5:32 EST 05/09/14 An earlier version of this story mistakenly referred to Nicolas Michaelsen as COO of AirHelp. He is CMO.