Damage to alarm system wiring

In March 2014 I spent R32,000 having 5 security 'slamlock' type gates made and fitted. I have no problem with the products themselves. When the gate was fitted in the sliding door/window space in the flat adjoining the house, I watched one of their labourers force a tight fitting aluminium frame into the relevant area, hammering it into an upper corner with his fist. The alarm wiring is visible in this corner and afterwards the system failed to set and would only do so by bypassing this section. They returned and loosened the frame and the wiring reconnected. I had replaced the 3 magnetic switches to no avail. I said if it fails in the future they must permanently fix what they damaged, only to be asked if I can fix it. IF I CAN FIX IT? The system is now giving constant intermittent false alarms indicating the window circuit is open. I phoned them about it and after 5 days with no response called again, when I was promised a return call after the weekend. 2 weeks later and still nothing. I was told that their T's & C's stated they were not responsible for any damage caused. I was neither given, shown or quoted any T's & C's. In future I will contract a more responsible firm.