Is there a gurantee when a battery was replaced?

In March 2015, a technician was sent to my house as the alarm could not be heard from our side(in the house). A battery was replaced and I was billed, R530.00. The beginning of this month, the same problem happened, an officer from ADT came thrice to my house in one day as they were picking up some fault on my front door. My kids called me, saying there was an officer who has been to the house and he even left the receipt for proof of visit. I then called the call center whilst at work and they said they could not help me unless I was next to the keypad. When I got home they say there was something wrong with the power of my alarm and they would like to send a technician to see what was wrong. As much as I am paying ADT on a monthly basis, can I really trust them when my house was ****** after their technician paid my house a visit in March and I had to pay them irrespective of the loss/damage that I incurred ? I was not given the guarantee that they would not charge me when their technician has diagnosed the problem. I am frustrated and frightened at the same time.