Paying for a non-existent service without my knowledge.

I received a increase letter today and decided to phone ADT to find out why the service is so expensive, The lady mentioned that I was also subscribed to some sort of Monitoring Camera that is in the street. There is no camera's in our neighborhood and never have I been asked to subscribe to such service. They cannot tell me since when this service has been activated, but I have now been paying over R50 per month for a non-existent service. I would like to be refunded since inception of such service.