Auto & General - Excessive Building Insurance Increases

Received my new premium increase for Building Insurance. They increased the building value by 8% and the premium by 24% !!. Over the past 4 years they have increased premiums by 52%. Inflation and building costs over the 4 year period will have increased around 20%. On a weighted average taking inflation and building costs at 50% of their costs then the balance of their costs/profit would have to have increased by about 84%. I have asked for detailed explanation of weighting and costs but got no detailed explanation. Sounds like they are *********** their clients compared to others in the industry. Very poor show.