The consumer group FlyersRights.org is petitioning the Department of Transportation to cap the fees airlines charge for changing international flights. It might prove a tough sell.

Changing a flight at the last second can be costly, especially if you’re flying internationally. But one advocacy group says the extra fees airlines charge go way too far, and it’s pushing the U.S. Department of Transportation to change the rules.

The consumer group FlyersRights.org recently sent an 18-page petition to DOT, arguing that the fees, which were once below $100, have ballooned as high as $750 in some cases. The group is calling for the agency to cap the fees at $100.

It might be a tough sell, however, as DOT has not weighed in on pricing since the airline industry was deregulated in 1978. In fact, the agency has declined similar petitions, including one submitted in 2012 by a Delta Airlines passenger who sought a refund or change fee waiver when an airline changes a passenger’s scheduled flight.

“DOT has the authority, but they’ve also acknowledged that in the last 36 years since deregulation, they’ve never exercised it, they’ve never denied a price or fee for being unreasonable,” Richard Baxley, a FlyersRights.org lawyer, told USA Today.

The airline industry says the fees are intended both to cover the costs incurred when passengers switch flights and to discourage fliers from making last-minute changes.

“The marketplace is working, and the petition doesn’t demonstrate otherwise,” Victoria Day, a spokeswoman for Airlines for America, which represents the nation’s leading carriers, told the newspaper.

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