Who's right my parents or me?

I'm 18 and living in my parents house. Evey time they ask for my help to let them burrow some money, they say they'll pay it back.BUT THEY NEVER DO. I'm still waiting for them to pay me back! they owe me about $900. They "bought me a car" and they say they don't own me anything, since all the money they spend on the car. The car did cost about $1200. So do they still own me money or am I in the wrong?