I'm self employed and work on the basis of a free phone consultation for potential clients (or in person if they come to my office.) Had a call set up last night. The time was their choice not mine, planned my day and evening meal around it ( which mean throwing my dinner down my throat when I came in from work and told DP he could fend for himself) and the person didn't pick up the call. It was only planned and confirmed less than 24 hours ago with their last email saying they looked forward to talking at X time. It was to a mobile so not really any excuse not to answer and no reply to my follow up email just confirming I'd try to call.
If you let a professional down in that way for an evening appt would you expect a bit of a curt retort for your thoughtlessness? (bar any terrible accident or event being the issue.)