South Dakota Insurance Increase

Their response is a bunch of hooey! They are just lying to you.
Creeping up rates is stand practice for all insurance companies now. They know that consumers don't like change, and will put up with increasing rates, as long as they do not go up too much.
Since you already contacted them and they lied to you, just send out quotes and change companies, that is all you can do.

I have said for a long time that I believe insurance companies are licensed thieves.

I had GEICO for 29 years, every year the rates went up. Then I sold the RV and the rate went down over $100/year (down to three cars) then came renewal time rate jumped up over $150/year, same three cars. I dumped them and went with another carrier. GEICO called me the next day stating they had a rate decrease for the state and if I came back to them I could get the insurance cheaper than the other company offered. I told them NO.

That's geico just like progressive they do huge increases for no reason