I am so glad you talked to the seller. So many problems can be solved with effective communication. In shipping things can happen. Good luck at the vet.
Don't look for a chicken vet, look for a vet that frequently deals with avian exotics.
I would ask the seller about the chick- ask if it is one of the bonus ones.
It could be an error, or an injury,. sometimes things don't go as planned despite the best intentions .
To me, it looks like a...