pathetic service

I am so in the dark with fidelity adt ,I had a two year contract because I was renting after two years I did not renew but was told I am on a month to month contract which I never agreed upon that was there own doing I stopped payment and for two years on and off emails asking them why am I being charged still every month and for two years as well they could never pick up a signal which they even informed me about I cancelled via email and was told I am handed over now my amount is 4000rand I need to pay,three or four weeks back they came to fetch the radio ...I think a couple of months earlier in 2019 I received a sms to say my contract is cancelled now. So I need to know where is the paperwork where it states you give them permission to deduct money off your account if you have not renewed the contract. A contract is a contract and I stuck by it for two years ...funny part is who says I even lived there as I was renting the place . I think its unfair that I have to pay this money also I had to replace my own battery thinking that's why they could not pick up a signal but it was not the case. So at the at the end of the day I have to pay for a service I did not even receive from adt. pressed the panic button over and over with no response but they have the audacity to charge me.