Useless scanners

On the 1st of June I took over the alarm adt system from the previous owner. Since the 1st of June until the 5th I had endless issues with the system. I then spoke to someone to cancel the system, a consultant then offered for a technician to come and check it out, to my surprise the technician don't pitch. I then again asked for this to be canceled. Now ADT wants to charge me Over a R 1000. For something that is faulty distorted and not working. I was told a manager will phone me today, guess what no phone call but you want me to continue paying. Please explain how I must pay for no service no support NOTHING.