The Department of Transportation (DOT) hit Southwest Airlines with a $200,000 fine Tuesday for violating the rules that govern airline advertising.

In January of 2013, Southwest advertised a one-way flight to Dallas for $66 and then failed to provide any tickets at that price. The next month, the airline promoted a sale that it undersupplied; it didn’t make enough seats available at the advertised price, which was “$100 or less” for nonstop one-way flights to certain cities.

The airlines are governed by the DOT’s “full fare advertising rule,” which requires that they include all fees and taxes in advertised fares, and that a “reasonable” number of seats be available at each advertised sale price.

“Consumers should be able to trust that the price they see advertised is the price they’ll pay for a seat,” U.S. Transportation Secretary Anthony Foxx said in a press release from the Department of Transportation. “DOT will continue to take enforcement action against carriers and ticket agents when our price advertising rules are violated.”

Photo Credit: A Southwest Airlines plane takes off. Associated Press