Sample
[DATE, ex. Wednesday, June 11, 2006]
[NAME, COMPANY AND ADDRESS, ex.
Robert Brown
XYZ Inc.
1234 First Street
Suite 567
Anycity, Anystate 85245]
Dear [NAME, ex. Robert Brown],
You must have forgotten our [DATE & TIME, ex. Wednesday, 2:30 PM] meeting. Although I understand how busy your schedule is, you have missed [NUMBER, ex. a total of three] meetings. Surely you can see that this is disagreeable and upsetting to me. Although I have tried to work around your schedules in the past, I am afraid I can no longer afford the risk of another unannounced cancellation. Regrettably, I will no longer be able to see you in the event of another missed appointment.
Sincerely,
[YOUR NAME]