Insurance not cancelled

In October 2015 I renewed my contract with MTN at the Cavendish Square branch. My previous contract with MTN had included insurance on my handset, however at the time of the renewal I was looking at different quotes for insurance and was not sure whether I wanted to continue with MTN's insurance. <br> The MTN consultant at the store advised me that should I wish to continue with MTN, I would have to contact the insurance department directly to set up the insurance on my new handset. I subsequently found cheaper insurance through another company and therefore did not contact MTN insurance, assuming my insurance on the old contract would be discontinued. When I received my account for November & December I saw that MTN was still charging me for insurance and was told that due to the fact that I had not cancelled the insurance directly, they will continue to charge me until it is cancelled. My complaint lies with the Cavendish store as at no point was I told that I had to cancel the insurance. I have tried to sort this out with the manager but have given up waiting for an answer from him.