Poor Service Back -up

Gerhard Lourens came to install 4 security beams and the criteria was that the wind and our 3 dogs must not activate the beams. After ensuring me that this would not be the case, he proceeded to install and had to come back numerous times as the alarm was triggered by the dogs and wind. I have paid me cash and in full and I have phoned and left numerous messages, but to no avail. He does not answer. So this guy cannot be trusted and I want him to come and replace faulty beams or sort out the problem. He just ignores me.