Security system never worked eversince installed

The system has never worked ever-since I activated it from the previous owner of the house. The consultant that I was signing the contract with promised to send a technician in September 2014, to date no one came but continued to deduct the payment. In December I left my house unsecured. I made numerous follow ups to no response. I wrote to cancel the policy and was responded to be told I owe the cancellation fee, when enquiring what service I have paid to date, there has been no response but continuing to deduct payments every month. I therefore want refund of the premiums I have paid as I never received a service from ADT