Thomas Nissan of Joliet

Took my 370Z to Thomas Nissan for an oil change, worked the night before so I told them I would just come back later in the day to pick it up. I figured it would be safe at the dealer where I bought it from. Went to pick it up and they told me it was around back, noticed it was the only one sitting there without the Service Number Tag hanging from the mirror, didn't think much of it, got in and started it up. Immediately noticed the low fuel light on. Thought that was strange because it was not on when I dropped it off. Usually when it comes on it will give a certain number of miles till empty, it was showing 0 miles. I check the odometer, and checked the paperwork odometer reading and realized 20 miles where driven on it. I confront the Service Manger asking him to explain why 20 unauthorized miles where put on my car for an oil change? He had no answer, but refunded me the 22 dollars for the oil change. I told him I don't care about 20 dollars, I care about what happened to my car while it was in there care. He noted my paperwork stating the unauthorized use. I suggested we ask the technician personally but he said it would be handled internally. This is not a car that someone would casually drive around town, I'm sure the guy beat the wheels off it. Disgusts me...My plates could have been called in on for reckless driving, street racing or worse.