Cancel Netstar Tracker

I am extremely appalled by Netstar's tracking service. I have been trying to get hold of them for week now to cancel the service due to the fact that there trackers are not accurate and because they are note providing the service that stated they would . I was given an email address to send a request for cancellation , I am still waiting on a reply I've called there number i was given to cancel *** and no answer . I have emailed there accounts department in the hope that someone can assist .... no answer. What is the point of having a tracking service if you are note available to answer your phone . I just hope that my vehicle does not go missing because this is a typical example that they would clearly note be able to assist in an emergency event. I want to cancel the service asap .