Dear Mr Smith,
Thank you for the invitation to the review meeting on the 12 July. Unfortunately, due to a prior commitment that I am unable to change, I will not be able to attend the meeting.
If you have any questions, please do not hesitate to contact me on my mobile, 6902341899.
I apologise for any inconvenience this may cause.
I hope that everything's going well over there?
I'm afraid that I can't make tomorrow's meeting. Something very important has just come up and I'm going to be very busy tomorrow.
I'm sorry for the short notice, but I just found out this morning.
Is there any chance we can put the meeting back until Friday?
Let me know if it's OK for you.
Dear Miss Garland,
With reference to the upcoming review meeting on Thursday the 13 November, I am afraid that due to personal reasons, I will not be able to attend.
Would you object if we postponed the meeting to next week? If this is appropriate, what day would be convenient for you?
If you have any questions, please do not hesitate to contact me on my mobile, 1902341892.
Allow me to apologise for any inconvenience this may cause.
I look forward to hearing from you.