815 ILCS 505/2FFF
All personal information relating to the customer of transmission, distribution, metering, or billing of natural gas service, or the customer purchasing the commodity of natural gas to be delivered through the distribution system of a natural gas provider, shall be maintained by the natural gas providers solely for the purpose of generating the bill for such sales and services, and shall not be divulged to any other persons with the exception of credit bureaus, collection agencies, and persons licensed to market natural gas service in the State of Illinois, without the written consent of the customer. It is an unfair or deceptive act or practice within the meaning of Section 2 of this Act for any person to violate this Section.
The provisions of this Section shall apply only to alternative gas suppliers serving or seeking to serve residential and small commercial customers and only to the extent such alternative gas suppliers provide services to residential and small commercial customers.
815 ILCS 505/2FFF