Changing insurance account without permission

I was paying R900 for my car insurance,all of a sudden January 2nd 2016,R1600 is debited from my account I thought it was annual increment but still seemed too much of an increment,2nd February R1700 is debited when I call auto and general they aay my account went under review thats why theres an Increase.i wasnt contacted about this increase after checking my emails there was nothing,iam frustrated that they can make changes to my account without me knowing better yet such a large increase