We have been with Grand Alarms for 7 years now and we have never really had any issues with their products. We upgraded to their wireless sensors system with no issues as well... I recently called them because i was getting error messages on my control panel regarding Low-battery life on some of my sensors.
They scheduled a tech to come in 1 1/2 days later, tech arrived on time, good communications and replaced/serviced all my sensors.
Very happy with their service and products!!