Kwikot don't want to replace their warranty product

My father in law's geyser got replaced via Kwikot no complaint. A month later my geyser burst and they told me it is out of warranty and it was installed in 2019. It supposed to have a 5 year warranty now they don't want to replace it. I contacted the service department multiple times but they don't want to assist. I even escalate to their manager Johan coetzee with no response from them. This is the service you get after you purchase something and when they see it is a female who is contacting them. I already had a plumber to have and come a look at it. Already had to go on expenses for something that's suppose to be under warranty still.