Unaccountable tradesmen

Used Herkie at 2 previous properties to add solar to my geysers and all went well. Recently requested him to install on a new build. Had a phone convo detailing everything on the Tuesday, namely that this was for a cottage in the back yard of my property. He needed to come round and just double check things again (had been there 6 months before during construction already). Friday he shows up at the house and is let in by staff, says he doesn't know where to go or what he needs to look at. Staff were unsure so sent him into the main house where he proceeds to inspect a random geyser in a roof space and in the process turns off the mains supply, in this difficult to reach roof space, to our upstairs en-suite bathroom. I contacted him shortly after discovering this, an hour or so after they left the premises and he refused to come back to open the valve again. There was no one on the premises able to get into that roof space so I had to call my helpful local plumber who climbed up there, turned the valve that I said would be closed and our water was back on, easy. Herkie flat out refused to accept responsibility nor to assist. Would not make use of his services again as if something was damaged by them they would just deny responsibility.