Refund declined due to no proof of cancellation

We signed up with chubb for monitoring our house in melville johannesburg on 24 March 2014. We were with them for 1year and 4 months. Unsuspecting we went unmonitored from the 17th of May 2014 to the 1st of July 2015. I realised in August 2015 that we were not monitored since the alarm went of and no response happened. Asking chubb the next day about it they said that they will look into it. That's when they told me that the last response they got from my alarm was on 17 May 2014. They never came back or did anything about it. Months later I called again asking for a refund to which it came down that they can't find a cancellation to refund me. Chubb didn't service me for 14 months, but they still took my money. Some people will call this ineptness theft. I call it lazy and oppurtunistic. Could somebody at chubb give me my money back?