Valid Claim - Rejection from OUTsurance

In November 2022, I logged a claim for my building / structure as the plastering of my property was starting to crack immensely. An assessor was sent out to review & claim was rejected as it was said this is not due to bad weather (Rain), the assessor also stated that no waterproofing was in place, like who waterproofs their entire estate. Now in January 2023, due to the recent rains the cracks had started to spread & it getting worse. OUTsurance refuses to approve the claim however it is valid that this had occurred due to natural destruction (Rain & Thunder). I have my vehicle, home contents & building all insured with OUTsurance but they refuse to consider me a valuable customer. They always giving you the highest premium & on negotiation it will further be reduced. I have no choice but to take this issue to the ombudsman for review as OUTsurance is being unfair with the decision making.