Want to cancel. No one is getting back to me.

I sent an email on 18 October to inform adt that I want to cancel as im relocating. No one has got back to me. Numerous calls have been made but it never gets answered. My alarm went off twice and when they call back I advise them of the above intention to cancel and the agent shut me down saying they can't help and I must call back the next day which as mentioned above is a mission. I sent another email and awaiting a response.