Pretend You Are Your Company's Customer
One of the best ways to determine if your service/business/organization is providing excellent customer service is for you, as a manager, to pretend you are the customer.
Try it today. Contact your business via the phone, mail, and via the web. Use all three methods! Make a different contact each day for the next week.
During those different instances, ask to reach a person where you only know their first name. Next time, ask for a person who no longer works at the business. Another time, complain about the service/product. Ask how to return a product. Or, you can pretend you want to talk to someone to learn more about the business. Try different scenarios that would be typical for your customers when they contact your business.
Then, observe what happens. I bet you'll be surprised. Hopefully, pleasantly surprised. But, you may be shocked. In addition to likely getting helpful assistance, you may experience people being rude or unhelpful. You may get bounced from person to person. Worst yet, you may encounter frustrating "rules and policies" or confusing explanations.
If you experience only good things, be sure to thank your employees who are providing that good customer service. If you experience things that need to be improved work with those employees and departments to make the changes necessary to improve your customer experience.