NOTIFY CUSTOMER THAT HE/SHE MISSED MEETING: FIRM TONE
You must have forgotten our [DATE & TIME, ex. Wednesday, 2:30 PM] meeting. In the future, I request that you notify me of cancellations in advance. As a busy person yourself, I’m sure you understand how badly schedules can be disrupted by unannounced cancellations.
Unfortunately, I believe our meeting would have proven quite favorable to you; [GIVE EXAMPLE OF WHAT CUSTOMER MISSED, ex. I spoke with our lead programmer, who informed me of a way our new order requisition module could save your firm a significant amount of money].
If you are still interested, call me at XXX-XX-XX.