Dear Kelly, 

I wanted to take a moment to thank you and let your future clients know that we are delighted with our basement renovation, It has gone from the space in which the children used to be reluctant to go (due to the werewolves, which were probably imaginary, and an unpleasant smell which was quite real) to their, and our, room of choice for being all together. 

Kelly, we wanted to emphasize that we really appreciated your clear and professional approach to all the complicated issues and factors involved in extensive renovation. You were really helpful to us, not only in the major arenas, but also in the collateral areas such as the leaking after the major rain a couple of months later. 
Again, thank you so much for your help. We’re really enjoying our new space, and I’m sure our “before” and “after” pictures should be pretty impressive to potential clients. 

Sincerely; Cynthia