Date :

[Select and type recipient's address]

Dear

Thank you for your kind letter regarding your exceptional treatment by one of our employees. A copy of your letter has been forwarded to the personnel department and will be included in the employee's file.

So seldom is it that a customer takes the time to write a letter of appreciation, that I feel moved to reward your initiative.  

Please accept the enclosed certificate, which, when presented, will entitle the bearer to a ten percent discount on the merchandise being purchased at that time.  

This is but a small token of our appreciation of customers such as you, upon whose satisfaction we have been allowed to grow and prosper in this highly competitive marketplace.

Again, on behalf of our entire organization, a heart-felt thank you.