A month after scoring its lowest rate of consumer complaints of 2017 to date, Frontier Airlines backslid in today’s U.S. Department of Transportation report on airline performance.

The Denver-based airline tallied 3.34 complaints per 100,000 passengers in July, more than twice the average rate of the nation’s 12 largest carriers, according to the agency’s latest monthly Air Travel Consumer Report. The average rate for the month was 1.58 per 100,000.

That’s the airline’s highest rate of…