Are there any changes to your file.There are a lot of factors that affect your car insurance.You can read most of them here:
http://goarticles.com...oung-Drivers/6099037/
Ask yourself, have you changed any of these?If so, make some changes.Ask your company why is this big difference.
If you think your company charge you more, you can go to any insurance comparison site.Register and get free quotes from all companies.That way you will see what is the cheapest rate for you.
Hope that helps