Warranty voided

Our burst geyser is 5 yrs inside the 10 yr warranty period - however Duratherm claiming the installation is non compliant!? Based on reviews on this site, and what I am hearing from our plumber, it seems Duratherm are voiding warranties on technicalities. Our installation was done in 2012 as part of the Eskom subsidy, by a reputable installation business! And the inspecting plumber (independent to Duratherm) informed me that the burst geyser was compliant - a spare, old geyser, was not. AVOID DURATHERM - bottom line in my experience is they are refusing what is obviously a faulty product!