Piano lessons schedule

Hi, guys, I am having a problem here and need some info for statistics. My kid is taking piano lessons from an awesome teacher. It is 45min lessons twice per week and we combine performance, technique, and go in depth on theory.

Whenever the teacher's in, everything's going smoothly. The problem is with scheduling. The teacher doesn't have a studio and instead is giving lessons in students' homes. I wouldn't mind driving my kid to his lessons but that's beside the point. Thing is, the schedule is becoming unstable, especially with the start of the summer break. During the year the lessons happen more or less on the same days and at the same time, however we are often being asked to move the time up or down whenever a student before us cancels the same day, or needs to have their lesson earlier/later for some reason, or if the teacher wants to go out of town for the weekend (one of our lessons is on the weekend).

With the start of the summer break it feels like we never know when our lesson is going to be. We know one of them is definitely on Tuesday but not sure which time, and another lesson is floating depending on what happens with other students. I asked for definitive times repeatedly but I am always told "I am working on it". We pay for all lessons in advance and also pay for those that get cancelled by our request. We can accommodate changes to some degree due to the teacher being really good for the actual lessons, but at this point the scheduling changes get more and more annoying.

Today the lesson didn't happen because the teacher simply forgot. It ended up in a not so nice conversation that is yet to continue, but that's again beside the point. My question is, is this fluctuating schedule a regular thing for private music lessons? Because it seems like not having a concrete day/time for each student hurts both students and teachers.