At least the piston heads will be scratched and dinged. Which will create hot spots and greatly lessen the life of the pistons and efficiency of the engine.
Based on your post, it doesn't sound like there was heavy impact. But the worst case is all of the bearings between the piston and the crank could now be damaged and that's not good. You'll be able to run it for a while but you will start to hear significant knocking and then you are out of options. You are looking at a new bottom end much sooner than you would have other wise.
Get all your facts straight, and go after them. They will fight you so you need to be able to accurately recreate the transaction and everything you discussed with the sales person. In the end it will be your word against theirs. Hopefully they will come clean. Good luck!