Nedbank, looking for ways not to play their part....

I have been with nedbank home insurance for 5 years now and few weeks ago I reported my roof to be leaking ,the assessor came and I was told that my claim has been rejected because I failed to maintain my roof? Like really how does one maintain a roof except painting it ?The Which I did if and when I saw fit. I am so frustrated....When I took out and insurance on this house that nedbank has financed the insurance came highly recommended, and because they helped me with the finance I thought this was their asset and would gladly assist whenever I go through such....Why do these insurance companies always find reasons not pay?