DQ do not attend to their appointments

I have made an appointment for each of my vehicles to have DQ removed. The appointments appear on their web site but the technician did not arrive. Now the appointment is marked as 'completed' when the units are actually still in my vehicles. The same thing happened when the units were installed - no one pitched. Now I cant even create a new appointment. I do not want the devices in my vehicles. They flatten the batteries and the product offering from Discovery is not-competitive and does not work as expected.