I agree with, the respectable thing to do would be to give you a refund.
You had the puppy less than 72 hours, it must have been heartbreaking for you to return it, especially for your son
I'm not a breeder, but I would have refunded your money, contract or no contract.
I would have felt like a thief if I had kept your money and turned around and sold the puppy making double off it
Can you pm me the name of the breeder? Someone I would scratch off my list...