Kwikot refusing to replace a geyser that is still under warranty

Kwikot is refusing to replace my geyser that is still under warranty, I am told that the geyser was not properly installed and my worry is that I am not a plumber I wouldn’t have known if the geyser is correctly installed or not and I was not even told all of that when I bought the geyser. My problem is I am not a plumber I no nothing about plumbing I would not have known that the geyser is correctly installed or not. I am just a consumer who went to buy a geyser and called a qualified plumber to install it.