Dear Customer:
As the manager of [COMPANY], I want to thank you for giving us the ability to serve you. As part of offering great service to you, please take a couple of minutes to tell us about the service that you have received so far. We appreciate your business and want to make sure that your highest expectations are met. Attached, you will find a coupon good for ...... We hope that you will accept this as a token of our good will and desire to serve you better.
Sincerely,
[MANAGER_NAME]
Manager