If you're here looking up Ameren Illinois customer care, you probably already know who they are. But it helps to get an idea of how big they are and what their support operation looks like if you are a customer. They are considered to be part of the following sectors and industries: utilities. Ameren Illinois is associated with terms like electricity (16, 900 megawatts) and natural gas, public by their customers and industry analysts. They employ 113 people according to customers in the know.