Airlines in the United States are doing much better, with few reports of delays, overbooked planes and lost baggage. Still, that has not stopped people from complaining, according to a recent Air Travel Consumer Report by the U.S. Department of Transportation released on Tuesday.

During the period from January to June, travelers submitted a total of 9,542 complaints to the DOT through email, phone or in person about air travel - roughly 20 percent higher than last year over the same period, where only 7,935 complaints were filed by travelers.

The number of complaints from a wide range of categories, namely flight delays, cancellations, refunds and baggage services, rose slightly. However, the complaints specifically about fares and customer services ascended alarmingly.

Complaints about fares, in particular "incorrect or incomplete information about fares, discount fare conditions and availability, overcharges, fare increases and level of fares in general," soared from 296 to 870. Meanwhile, issues on customer service pulled 1,121 complaints, which is a lot more than the 832 complaints lodged during the same period the year before, according to Money.

Spirit Airlines, an airline based in Florida, received the highest complaint rate, with 19.16 complaints per 100,000 passengers, according to the Los Angeles Times.