"I just wanted to say how pleased I have been with your excellent service. Your initial help on the phone was friendly, intelligent and to the point. Your price was the best of 3 online suppliers I tried, and a whole lot less than my usual optician. Finally I couldn't believe how quickly you got my new specs (which are perfect by the way) back to me, in well under a week.
We all spend a lot of time moaning about poor service of one kind or another, and it's nice to occasionally be able to praise a company for actually exceeding expectations. I'll definitely use you again when I need new glasses. Thanks. Kind regards"