"I truly appreciate your excellent customer service, and I will recommend you to everyone I know."
"Thanks to a very capable, patient, and pleasant member of your support team, this program is doing all and more than I hoped. I can assure you that you will be my choice for all future software needs, and that I will recommend you to others."
"Thanks for all of your help. I did not expect you to work on a holiday weekend and was not expecting anything until the following Tuesday."