Hey, no one's perfect – and certainly, no airline is perfect. United is one of the world's largest carriers, operating an average of 4,800 flights at 353 airports each day. As with any business that serves millions of customers each year, United leaves some of them displeased. The airline provides several communications options for dissatisfied customers. Any one will connect you to assistance, but some complaint methods are more likely than others to pay off.

Complaining in Person

If trouble arises while you're in the airport, or you want to complain right after you get off a flight, head straight to the nearest United customer service desk. Usually a terminal that serves United flights will also have a staffed help desk. A gate agent or ticket agent may also have the necessary authority to address your problem.

Remember, airline staffers take a lot of abuse from stressed and unhappy customers. Being friendly, patient and polite will sometimes make an agent more inclined to go above and beyond to help you. Vowing that you'll never fly United again won't motivate an airline employee to help you.

Complaining Online

Using United's Customer Care portal is an efficient way to contact the company. By logging into your MileagePlus account, the site will automatically fill in some personal information and your recent flight information. Then, all you have to do is write a description of the issue in 1,000 characters or fewer.

Using the airline's social media channels is a good option if you want to complain about something in real time. Tag @united on Twitter, or send a direct message to contact a customer service rep privately. During business hours, United staff tend to reply fairly quickly to tweets from distressed customers. This is a viable way to resolve minor issues, such as getting answers to questions about flights, but don't expect to get a refund or resolution to a major issue over Twitter.

Complaining by Phone or Mail

Online communication may be popular with modern travelers, but United is still reachable by traditional methods. Customers can contact the company with complaints by phone or by mail. (Don't bother dusting off the fax machine: United, like many companies, has totally phased out faxing.)

There are two major United Airlines phone numbers, and the one you need depends on the nature of your complaint. If you need an urgent solution to a problem, such as if you've been bumped from a flight, call the main customer service line at 1-800-UNITED-1 (1-800-864-8331). To complain about a past trip, call the company's post-travel feedback line at 1-877-624-2660. It's a voicemail system, so think in advance about what you want to say.

Prefer to put pen to paper? Send a complaint by mail to Customer Care, United Airlines, Inc., 900 Grand Plaza Drive NHCCR, Houston, TX 77067-4323. Include your MileagePlus number, flight numbers, confirmation numbers, and any other supporting information related to the issue or include copies of your travel documents.

What to Expect From a United Complaint

No matter how major or minor your complaint, expect to hear back from United Airlines customer service. The carrier has a commitment to acknowledge written complaints within 30 days and to provide a "substantive written response" within 60 days.

The key to getting what you want from a United complaint? Be ready to name the exact kind of action that you want the company to take, and make sure your request is reasonable. If you were stuck in a broken seat, for example, United may be willing to give you some airline miles as an apology, but don't bother asking for a $5,000 travel voucher.

If United doesn't address the complaint in a way that you deem satisfactory, file a consumer complaint with the U.S. Department of Transportation. DOT will contact the airline on your behalf. Absolutely contact DOT if you feel you experienced discriminatory treatment.