trying to order the dvds that are 50% off

[PoeticLicense]

I do not understand this. It says a selction of 14 DVD sets are half off. When I put it in my cart it is full price. I contacted CS about this and they said it is out of stock. But it's not. I can pay for it at 2x the price, just not the advertised half price. What is up with that? Any ideas?

 

TIA