I have been waiting for a technician since Tuesday to come fit a new tracker on my car

I have been waiting for a technician since Tuesday to come fit a new tracker on my car. When I called Tuesday to check why they have not arrived at 8:30 since appointment was at 8am, I was told that the technician is coming as soon as he finishes his first appointment as 8 had double bookings. Late on the day no one came, I was told they want to reschedule my appointment the call center cannot reach technician to find out why he didn't come. Appointment was reschedule for today which is a Friday and the same thing is happening.