insurance company add someone to my policy without my permission

Yes and No.   Can the insurance company do this... well, yes they can and they did.   Is the insurance company allowed to do this - Most definitely not with out some kind of prior notice and on policy renewal.  If your cousin is a young driver and frequently drives your vehicle and somehow your insurance found out about it then the insurance can insist on her being on the policy and charge you more.  However they can not change your policy mid-stream without written notice.   You likely have a contract claim if they changed your insurance contract without notice.    I'd call your insurance agent first and see what he/she can do about it.   An attorney will cost a good bit more than the difference in the premium however you don't want to have to continue to pay that outrageous sum.  You can always call your carrier and expressly exclude your cousin which would mean that they would not cover you if she is driving your car.   In theory that would return your premium to what you were paying and even possibly some less.... but then DO NOT let your cousin drive your car. I'm not your attorney so this is just friendly advise.  If your insurance doesn't return your money and resume the premium you agreed to then you should hire an attorney to recover those funds.  As with most consumer products you can let your $ do the talking and switch insurance carriers.