Wusses.
You have ALLL the leverage. Have fun with it... Seriously. How many chances you get this much leverage in life?
Step 1. Have your attorney write up something showing them what they did wrong and how you can take their ass to town.
Step 2. Demand 5 Times their original price or you file it.
Step 3. AFTER they pay you, demand more. Tell them it's for mental anguish. Remind them that they don't have a choice.
Step 4. AFTER they pay you more, tell them you already sold something like this to their competition. (Which you could actually do for even more money...) So it might be worthless by now.
See what I'm getting at here? You just struck gold.