While I agree that the animal needs to see a Vet, the down side is that once you take her to the Vet, it kind of becomes your problem. I have a hard time believing any seller that would ship a snake in that condition will be quick to help with the Vet bills.

Of course, the circumstances around this whole snake seem a little sketchy, so this may be your problem already. Fingers crossed that the seller will let you ship the snake back.