Cdn logistics Screwed me out of my security deposit North lake Illinois

 I worked for Cdn logistics as a lease operator. I leased my equipment from another company. I decided this wasn't working out and returned my truck to the lease company and all the stuff from Cdn back to them. I had a security deposit which was taken out of my check and was suppose to be returned. It's been almost 3 months and now they are saying they aren't returning it. That was my money and I owed them nothing when I left. I even received my last pay check from them. I want my money back. I did my part and now they are screwing me over.