Geyser installation cause damage

Absa's *********** contractor installed a Geyser after the installation there was no hot water in the kitchen, the alarm system's sensor malfunctions where the installation took place and the main power switch is tripping. They came on Friday claiming that the problem was with the valve of the tap in the kitchen which had to be replaced. They did not open the valve to test their theory but made an assumption. We did replacemente it and still no hot water. We demand that the damage be corrected