I've had a tracking unit in my car for over 3 years but recently it's stopped working and I've been trying to get a technician to check it out

I've had a tracking unit in my car for over 3 years but recently it's stopped working and I've been trying to get a technician to check it out. From being told that someone would call me to their lines not being clear I'm having the worst experience. I've been trying to reschedule the appointment I finally got because the car is not with me but their lines are inaudible, I've called back numerous times.