Social media empowers companies to connect with customers. It enables companies to listen, respond and promote itself, among a plethora of other things. Social media, however, also empowers customers to get back at brands, as we’ve seen this summer in the United Airline’s “United Breaks Guitars,” debacle.

Last year, when United Airlines’ workers broke musician Dave Carroll’s $3,500 Taylor Guitar, the airline refused to compensate him for the damage. The repairs cost $1,200. In a final offer, Carroll even said he’d accept $1,200 worth of flight vouchers, in compensation for repairs. United Airlines still rejected the offer.

Fed up with nine months of battling with airline representatives, Carroll realized he was not going to win the battle. During his last call to United Airlines, he made a promise to do something that would cost more than the guitar’s worth to company’s reputation.  In fact, some claim that what he did could have cost United Airlines $180 million. His weapon for bringing down United? YouTube.

Not only did the musician use YouTube to trash United’s reputation once, he did it twice. And he plans to do it a third time. His first video now has more than five million views, and the second, released two days ago, has surpassed the 100,o00 mark.

Of course, United contacted him immediately after the first video, offering compensation for the broken guitar. But it was just too late.

There are two important lessons to learn from this.

First, web-savvy customers have the power to use social media just as effectively as big brands do. Two videos can be detrimental to your online reputation. And if the customer causes a big enough stir, the story will get some play time outside of the social media realm.  When Google-searching “United Airlines,” on the first page you’ll see Carroll’s “United Breaks Guitars” videos. On the first page of the “Southwest Airlines” Google search, you’ll find Southwest’s blog “Nuts About Southwest,” which is  highly interactive and an example of outstanding social media execution. Lesson learned? A customer who knows a thing or two about social media can trump your company’s social media efforts.

Second, customer service is still king. With a pretty impressive following of 31,000 on Twitter, and a meager Facebook presence, United Airlines is doing OK on social media. Social media provides a platform for a brand to listen to and interact with customers online. Listening online, though, is not enough. Social media isn’t the end-all be-all. Brands  need to focus on a comprehensive strategy. One that includes social media AND outstanding face-to-face customer service. United Airlines didn’t do that, and now it is the one paying the price.