Netstar is "*****"

I am with Netstar , account number ***3. I have two tracking devices installed in our company bakkies. We sold one bakkie during the lockdown and since then struggles to get Netstar to remove the unit from the bakkie that was sold and install it in our new bakkie. They still bill me every month ,although they know the unit is in the old vehicle. My insurance and myself contacted Netstar several times to make a booking for them to install a unit in our new bakkie. The client services lady called and we made a booking for today 13h00. I also informed her that the bakkie will be on a construction site, because we use it for our business. The technician arrived at 14h00 on site, only to inform me that he cannot install the unit, it is against protocol because the site is not secure. What nonsense, my other bakkie was fitted on site. It is not against Netstar's protocol to take your money every month for something you do not have?