Momentum Geyser Replacement Issues

I have logged a claim for a burst solar geyser. Momentum has allocated a plumbing company that will not assist to install the replacement as they insist on me providing an engineers report for the roof. The solar geyser is currently on the roof....so they mention like for like replacement..........is this not a like for like replacement. This is totally ridiculous and I am not impressed. I have never been informed ever that in case of a replacement i would need to provide the certificate. What annoys me even more is the fact that the geyser was replaced 3 tears ago by the dame service provider when it also burst. I want this sorted ASAP. Its been 4 days and we are no where near a solution. Is this how you treat your customers. Really disappointed. Get another plumber to assist. I want this resolved asap.