Tracking canceled by someone else without notice

Netstar cancelled my tracking without my authorization. They canceled it based on a letter received from someone who had nothing to do with me or with my ID number- Just the reg number. I received no notification and only when I called to test the unit was I told it was canceled months before. How is this even possible ? That means that anyone could just write a letter with my car registration number on it and get it canceled then ***** my car and it would have no tracking. This is unacceptable. \Well someone made a mistake"- Not my problem. Service was reactivated Oct 6th but after advising my insurance company of what Netstar did they suggested I change providers"