Terible service

On friday the 18th of Feb ADT came to install an alarm system at my house, I told them to make sure the first payment goes off the end of Feb, they said yes then comes the sat they take off the first instalment then they phone me to say there is a problem with my new systems battery a technician will come and fix it the Friday afternoon at 2 which I am still waiting for them and its almost Sunday. I also phoned them to change my code and the lady said my code is changed successfully which it was NOT done it was still my old pin. I feel after having so many problems I want to cancel my contract as they already breached it within a period of 7 days which is not acceptable and rather go over to BLUE