456, X Street, Y Avenue,
[Subject: Normally bold, summarizes the intention of the letter] -Optional-
Dear Jack Martinez,
A scheduling conflict has come up and we regretfully cancel our reservation for this year’s seminar. As we have already paid for our advertising in the annual brochure, we hope to still be mailed a copy. At this time, we will make a determination as to whether to buy multiple copies of the brochure. My understanding is that this will be available in the next three months and I look forward to seeing the quality work you have put together.
Thank you for all your efforts. I am sure the seminar will be as successful this year as it has been in year’s past. Good luck and best wishes on your business success.