It depends if you are in the mood to keep fighting or just move on and take the 100 dollars.
I don't know what I would do. If you feel that you were really treated unfairly then I would write delta again, saying through "thank you for the response but..."
Or I would take it up as a bad travel experience and move on.
It depends how much time you want to invest further in this. Anyway, you got my support, whatever you do! CATMAn