Geyser replacement service is terrible

After hours on hold, I finally got hold of someone regarding my burst geyser. Once they sent a plumber out, he informed Standard Bank insurance that the geyser is under warranty. Standard bank insurance then told me that they cannot help me because its under warranty. The Gap geyser company is being liquidated and no longer stocks these geysers. So Gap is offering a cash refund of R4900. I am now being quoted R8000-R12000 for this geyser replacement. How is it that I have insurance, but need to fork out between 3-7K out of my pocket to have my geyser replaced. This is the reason I have insurance! Yet they deduct my premium every month, which stated that they are covering my Geyser even though they know that they wont cover it for the first 5 years!