Billing for inability to provide service paid for

I bought a house fitted with an ADT alarm with Radio Pad. I had ADT activate the service, all they had to do, was to monitor the alarm and inform me if it goes into alarm.<br> <br> On various occasions I tripped my own alarm on accident, but received no call from ADT. After contacting them, they would send out a technician, each time they play around with the radio pad and swap it for a different unit. Each time it only takes a while before I find out that the device is not working properly.<br> <br> After the third attempt to have it fixed and after I requested that they move the antenna closer to the roof (it is flat on the ground and I live in a valley), the technician told me that I have a funny house and that is probably the cause of the problem.<br> <br> Each time, the technicians were late for the appointments.<br> <br> Needless to say, I cancelled my contract, but I still got invoiced for second hand equipment that was swapped with what was legally mine and removed. Also the radio pad was not properly fixed like the original was and is hanging from the wall. <br> <br> Now they want me to pay up? For what? I signed a contract for a service, not to have stuff hanging around in my house and be an eyesore