The U.S. Department of Transportation last week fined United Airlines $350,000 "for failing to make prompt refunds to consumers."

Between March and May last year, United "failed to process over 9,000 refund requests in a timely manner," according to DOT, which requires airlines to process credit card refunds within seven days and check or cash refunds within 20 days. DOT also cited, but did not fine, United for inaccurately reporting mishandled bags and oversold flights.