Shocking service and attitude

Duratherm guarantee their geysers for 10 years. Our geyser is 3 years old and rusted. They refuse to replace the geyser claiming our plumbing is not compliant even though we have a Certificate of Compliance for our plumbing. They keep sending plumbers to our house to take photos and do nothing else. One of the plumbers they sent replaced the pressure release value and positioned it incorrectly and this is the excuse they are using as to why they refuse to replace the geyser, when it was one of their people who positioned the valve. They keep passing the buck. Their staff is unhelpfull. I would NEVER recommend their product!