Cancellation and billing

I will like to place a complaint on chubb. I had take out a contract with chubb in july of 2010 which was a 36 month contract which ended in 2013 . I did not sign up a new contract in 2013 or 2014. In september of 2014 I called the call center and canceled . I was told by the call center agent that I did not sign up for new contract with them and I can cancel my debt cause it was on month to month . Also he said that if I remove the radio and gave it to the tech when they came I won't be charged which I did. I had also sent a email to cancel . I keep getting letters from chubb saying I need to pay them for removing of radio and 3 months. When I called the call center spoke to a manger she said that I signed a contract and it states I must give I 3 months notice and they techs came in and removed the radio I asked for proof of a tech coming into my home to remove the radio which they don't have and where is the contract I signed after 2013 which they don't have . Why am I been charged for something that I had not renewed also that chubb tech did not remove .