Your company’s brand represents the value customers receive when they interact with your business. It’s a promise of sorts: When you choose to purchase from us, this is what we will deliver to you. When you break that promisethrough defective products, shoddy workmanship or poor service—you may just lose the customer. And in this age of social media, you might also lose your reputation, too.

Remember the musician who made a YouTube video about United Airlines breaking his guitar? It was a PR nightmare for the airline. His video was viewed more than 12 million times and spawned a whole culture of people creating videos to showcase their service complaints.

How can you avoid making service mistakes that hurt your brand? And what can you do if those mistakes happen (as they will on occasion despite your best efforts)? Here are four insights culled from recent experience.

The U-Haul “reservation” that wasn’t. We recently arranged to rent a truck from U-Haul and made a reservation weeks in advance. We also confirmed a few days before our move date and phoned on our way to D Jay’s Service Center to say we were on our way. But when we got to D Jay’s, our truck was gone. Though our reservation form didn’t indicate it, apparently there was a set pickup time. When we arrived past the pickup time, we found that D Jay’s had rented our truck to someone else. No other trucks were available.

U-Haul finally got a truck for us four hours later, but the damage was done. We’ll never again rent from U-Haul. And because I’m on Facebook and Twitter, thousands of people may hear one unhappy customer’s story.

No one’s perfect—and social media can make it worse. All companies make mistakes and some customers will forgive and forget. But some won’t. Unhappy customers who used to gripe to their immediate family and friends now can share their dismay with everyone. When your company makes an error, social media can dramatically magnify the problem.

Four lessons. How to avoid service mistakes and mitigate the impact on your brand when you or your employees do goof up:

  1. Train your entire team about what your brand promise means. It’s no accident that companies with great brands have great people who consistently deliver excellent service. Make sure everyone who interacts with your customers understands your brand promise and how to make that promise real for every customer every day.
  2. Admit it when you screw up. If your company makes a mistake, be upfront about it. Don’t blame the customer or come up with lame excuses. It never works.
  3. Make it right. Show your customer why this error was an aberration by fully resolving the problem. If you do this right, the customer might tell a very positive story about his or her experience with you on social media.
  4. Monitor and respond to social media complaints involving your brand. When an unhappy customer posts something negative online about an experience with your company, respond immediately. Be empathetic, then attempt to take the conversation offline so you can resolve the complaint.

How will U-Haul respond when (and if) they read this blog post? It will be interesting to find out.

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Jean M. Gianfagna is a marketing strategy expert and the founder and president of Gianfagna Strategic Marketing which provides marketing strategy and creative services to leading business-to-business and consumer marketers. Read her blog for more marketing tips at http://www.gianfagnamarketing.com/blog.