Confusion at Tracker.

I took out a contract with tracker in March this year for an "early warning device" which they assured me they can install. Their technician then arrived at my house and installed the tracking unit and again assured me that it is an early warning device. He then said to me that I need a tag on my key for the device to work properly, but that this tag would be delivered to me by his manager within a week. 2 Weeks later I was contacted by my insurer to inform me that the unit installed in my vehicle is not a early warning device. I then contacted Tracker to find out what the problem was. They then explained to me that they do not have the tag that has to go on my key in stock and they said it will take months to get stock. So Tracker could not provide me with the unit that the insurer needed me to have installed. I then switched to Cartrack. Numerous personnel from Tracker called me afterwards and the next person said the "early warning system" doesn't exist. This is confusing and poor service. Tracker keeps on phoning me on a weekly basis to ask me about payments. How do they expect me to pay for half a unit? Every time a consultant contacts me its a different story.