Fed up

Worst company ever I had a contract with them which expired in August 2015 and I cancelled a month before the time which they asked me now in January 2016 they send me message that I owe them apparently I didn't cancel my contract which I did m spoke to person to confirm cancellation last year. I already did not have a pleasant experience with them as I think we paying them for nothing they don't even do patrols in the area n comes out almost a hour after alarm goes off why would I not cancel my contract with them? I am fed up with the company that only wants o exort money from us but don't render the service they suppose to