Shocking geyser broke twice in under 2 years, still under warranty but they won't sort it out.

Installed a new geyser a while back. First the element broke literally 1 month after the warranty on the element ended. After an expensive repair it worked for a short while. Now the actual geyser has burst a seam. Our plumber confirmed this should be under warranty. An incredibly rude person from Heat Tech came out to look at the geyser and told us its some other part of the geyser, like a pressure valve, and the warranty on that has expired. My plumber completely disagrees, but we need hot water, so we have to install a new geyser. I will never use a Heat Tech Geyser again!