Insurance lack of accountability and responsibility & contractor gross overcharging

A recent claim lodged was rejected. I had to seek professional experts to validate my claim. Work done but no sign off by owner? The original contract invoice increased by 70%. The only reason I found this out was that my insurance premium increased by 25%. I then requested to see the contractor final invoice. I found gross over charging which Discovery should have picked up. Why should the client monthly premium increase when Discovery has lost touch with market related pricing..Do insurance companies work in the best interest of their business, the client or the contractor. Is a vicious circle that appears to be out of control and lack of accountability and responsibility by insurance.