My question involves landlord-tenant law in the State of: Illinois (Chicago)

I moved into my current apartment in 2007. When I signed my lease, it stated that water and heat would be included in the monthly rent. However, after I moved in, I was contacted by the gas company asking me to set up an account to pay for gas. I figured that this would be for cooking gas, which would be separate from the heat.

It turns out that I was paying a monthly bill for both cooking gas and heat. Am I able to charge my landlord for the money that I paid to the gas company? The landlord was supposed to pay it, not me. I still have the lease that states "HEAT IS INCLUDED" and it's actually in caps!

Thank you!