
Thomas and Applegate recommend telling your customers "Thank You" during at least these nine situations:
When they do business with you...every time.
When they compliment you (or your company)
When they offer you comments or suggestions
When they try one of your new products or services
When they recommend you to a friend
When they are patient...and even when they are not so patient
When they help you to serve them better
When they complain to...