Worst Service Provider

I'm unhappy fleet customer of Cartrack, on January this year I requested for De and Re from cartrack which they sent a technician that came and DE install the following day and after 3days another technician did RE install but only the tracking equipment without the camera and debited my account R870 twice for the service upon my account is up to date but they are unable to RE install the camera I tried to call them so many time but keep posting me from pillar to post, my question is why debiting my account for three months for the service they are not providing and so many times I have disconnected my battery terminal without a call from cartrack that means they are not tracking the car. please I need a help to end this contract because they are de*****ing me by debiting my account every month for service they are not providing, I want my R1740 and three months payment back.