Bad service, lack of communication

Why is there no option to not rate? I signed up with telematics in August, they then came to install their tracker. I opted for the Geo-lock on my subscription but their tracker has never worked for me, I phoned to inform them and also lodge a request to check my tracker they promised to phone me back. Never received a call from them, I phoned for several times until I decided to send them an email of cancellation on October. I only received an email with the case number but when I call it's either they don't answer or they send you from pillar to post, I've been receiving threatening messages to handover my legal collection from due to non payment. Why do I have to pay for something that doesn't work for me. They have poor service, lack of communication. I cannot keep on using my airtime to call them for their lack of service and beg them to assist me.