Ever since I took the insurance cover, but they keep on increasing the premiums

I honestly don’t understand why discovery insure keeps on increasing my car insurance premiums each year. This year, they decided to increase my premiums with close to R400. Last year it was the same, this year again? I find this practice unacceptable especially for someone who never claimed since taking the policy almost 4 years back. If we proceed like this, my insurance premium will soon equal to my car instalment. I am searching for a new car insurer.