No response on a 9.1% hike on premium

My policy premium went up this year with 9.1% I wrote to Momentum asking them to explain why this went up with this value, no response at all. This is not acceptable that a premium can go up with this amount. Why does a customer always need to log a complaint before the business will respond?

Customer service is going down the drain. I need email feedback and not a phone call so that i have a reference later