Unfair treatment

I have been a client of the company for a few years now and I had a geyser burst which I lodged a claim for in February 2017, I was assured a 5 year warranty after being replaced. To my surprise, on the 3rd August 2019, I was awoken by water tripping from a geyser. I lodged a claim with the insurance only to be told that the warranty has lapsed when the plumbers assigned to my house came and investigated? I feel this is a raw deal and I am reluctant to pay the money they require for the 5 year warranty is still on...