Again, appointment canceled without notifying me.

Again, appointment canceled without notifying me.
It is the 4th time with them.
The first time, the person in charge of my car was sick, then he was in training and the third, I am not on the schedule while the day before, I received a confirmation by SMS.
This time, he is in training again and nobody of course called me to change the date when it was given to me more than 3 weeks before coming on site.
Each time I take a day off or shift my schedules. In short, a waste of time.