Bad service and i must be with them for 20 years , and its only 2 months now

Bought a house 3 months ago. Only registered on my name a month and a half ago. Took insurance through Nedbank insurance. House was valuated by nedbank before purchase. After last weeks rain the flat on the property i purchases roof leaked every where damaging the ceilings. Had assessor out from Nedbank. Guy says he does not think Nedbank will cover it because the roof ontop looks like its in poor quility. When i purchased the house Nedbank should have told me that the roof is not in good oreder, then i would not have purchased the house. When itook the insurance , they should have come to asses the condition of what must be insured. I feel cheated, and i feel that i pay a lot of money for somehing which is not 100 %