456, X Street, Y Avenue
[Subject: Normally bold, summarizes the intention of the letter] -Optional-
Dear ANDREW HALL,
Words cannot express my disappointment at having to cancel my appointment with your art gallery. I have waited many years to find a beautiful piece of art to hang in my home.
I’ve been told your gallery is the best at finding the perfect piece. With this in mind, I’d like to schedule a future appointment right away. I understand the waiting list is long but I am willing to be patient.
It is unfortunate I must cancel but circumstances were unavoidable. Please call me with a new appointment time. I look forward to hearing from you.