(AP) – Three U.S. airlines have agreed to each pay hundreds of thousands of dollars in fines to settle government claims that they violated rules aimed at protecting consumers.

The Transportation Department detailed the violations and the fines levied against American Airlines Group, Delta Air Lines and Frontier Airlines in documents released late Friday.

The government found that American failed to make timely refunds to passengers, and Delta underreported the number of mishandled baggage complaints it received from passengers.

Investigators determined that Frontier involuntarily bumped passengers from overbooked flights without first seeking volunteers or providing proper compensation. The government also found that Frontier failed to assist disabled passengers.

American agreed to pay $250,000. Delta will pay $200,000. Frontier agreed to a $400,000 fine.

The airlines did not acknowledge or deny wrongdoing.