> the tech calls that he''s not coming to our appointment.
I feel sorry for that technician. Obviously, one (or more) of his other customers with scheduled visits on the same day has gone much longer than booked. Given that their [gender-neutral pronouns are used in this posting] employer might not have allowed they to work overtime, something had to "give", resulting in the cancellation of your appointment.
Maybe, they are a single-parent, with responsibilities to return home at a specified time, to take care of their family, and those responsibilities are more important to both they and their employer than "missing" an appointment with you.
Was your appointment booked for early in the morning, or late in the day? I suggest that you re-schedule for an "early" appointment, to increase the probability of the technician arriving on-time.