scam artists!!

In December 2018 part of our garage roof collapsed during a violent wind and hail storm. Compass insurance sent an assessor in January 2019 who duly rejected the claim as saying that it was an original design fault of the roof trusses which were installed, and approved by a building inspector, thirty years ago. so why didn't the whole house then collapse?? my argument is - who do we believe - a building inspector or an assessor? the installed roof trusses, together with the whole house was signed off and approved by a building inspector when the house was built 30 years ago - why is it now a design fault??? especially as it has lasted 30 years already - i think that it is just a lame excuse not to pay the claim. we have been paying insurance on the house without one single claim and now when we do have a claim, it gets rejected??? together with our Insurance brokers, RBS Insurance brokers, who are no help to anybody at all, I have never been so disappointed in a company in my life!!! all they do is take your money and find excuses not to pay - so why bother to have insurance at all?????