United Airlines was slapped with a $2.5 million fine by the U.S. Department of Transportation for violating consumer rules and handling flight delays. The department investigated the airlines after an increase in complaints from disabled passengers and five delays in the past two years.

According to the Associated Press, the DOT found that United Airlines failed to give disabled passengers quick and proper services in getting on and off planes while also providing damaged or delayed wheelchairs. The second-largest US carrier was also fined for the flight delays where passengers were kept waiting for more than three hours at O'Hare International Airport in Chicago last Dec. 8, 2013, and at William P. Hobby Airport in Houston on May 20, 2015, due to bad weather conditions.

"A review of these disability-related complaints revealed that United failed to provide passengers with disabilities prompt and adequate assistance with enplaning and deplaning aircraft," the DOT said in a statement via the Los Angeles Times.

The $2 million fine was for violations against disabled passengers while the $750,000 was for the flight delays. United announced in their bulletin on Thursday that they will spend $150,000 for the improvement of the company's audits of its wheelchair providers while an added $500,000 will be for the development of a new technology on easier passenger wheelchair requests.

The technology is a mobile application for both passengers and crew for a better and quicker wheelchair service. United will also spend $375,000 for a better plane parking system that will reduce taxi times during a winter storm.

"We expect this to greatly improve our ability to have wheelchairs where they need to be, when they need to be there, so that our customers can get on their way home or to their next destination with ease," said United Airlines Senior Vice President of Airport Operations Jon Roitman.

The latest incident involving United and a passenger was back in October 2015 when D'Arcee Neal, a man with cerebral palsy, reportedly crawled out of his seat because a special wheelchair that fits in the plane aisle was not immediately available. The airline acknowledged the incident and quickly gave an apology to Mr. Neal plus $300 compensation, per NBC Washington.

In a report by Reuters, United Airlines is not the first carrier company to be fined by the DOT. US Airways was given a $1.2 million fine in 2013 for poor wheelchair assistance policies at two airports while Southwest Airlines was fined $1.6 million last year for breaking the flight delays ruling.