Adt security unfair treatment

Adt sales agent came to my house in Benoni. He was promoting their new app called find me. I was interested and the sales agent asked me to sign the contract and he will call me to help me activate the app. He didn't call me and the app was never activated. They started deducting money from my account even though they didn't provide their service as promised. I tried to call them but no one seemed interested. I started desputing their transactions with my bank everytime they deduct money from account. Now they are sending me invoice to say I owe them but they never provide the service they promised me. They are *****ing my credit record. I'm very unhappy. Someone from Adt please assist.