And, Shawn, I seriously disagree with you.
While, yeah, you should confirm the gender of the animal yourself when you recieve it, it is not your fault if the animal ends up being the wrong gender. Not even if you find out months or years later. It is the seller's fault. I do not really comprehend you thinking it is all your fault, but if you want to take some of the blame, okay, I cannot stop you from doing that.
Most breeders have TOS that cover missexed animals. I know I do.
In this particular case though, I am not sure what the OP is trying to get out of this. It seems to me he was given an option to fix the situation which, to me, seemed reasonable, but he refused it. He wanted another animal, as he said, but did not want to pay the gap in difference between the two. He also may have been really aggressive about it, which is not generally something that should be done by buyer or seller.
While it may be more obvious that the buyer should hold himself in a certain way when doing business, customers really should do the same. Being angry is understandable, lashing out a bit is understandable, physically threatening someone's well being is not. Generally, this forces the other individual into a defensive stance and it leads to an unstoppable force meeting an immovable object.
Obviously, that can only end in a deadlock.