What are good examples of companies that have top customer service? Why?

Don't make promises unless you will keep them

KLM Since the eruption of Icelandic volcano Eyjafjallajökull in 2010, KLM has become a leader in the social customer service field.
With the volcano eruption, flights were cancelled and thousands of stranded passengers turned to social media for help.
KLM was there, armed with the same channels to “respond more quickly to customer inquiries, re-direct them to other means of travel, and protect the KLM brand image,” explains Viktor van der Wijk, Director of Digital Marketing at Air France KLM.
It was the perfect example of a crisis averted with social media, and triggered a fundamental change in the way KLM handles customer service.
Now, KLM places social media at the center of all their customer service efforts, with a precise goal to cut response rate to one hour and have all major issues resolved within 24 hours when dealing with posts and tweets.
They do this well, with a 24 minute average first response time and a 92% post response rate to questions asked on Facebook.
KLM continues to go the extra mile to reach out and connect with customers through constant, creative social customer service campaigns like the Live Reply campaign or KLM Meet & Seat program, which they showcase on their Social Journey Facebook tab.