Ok, well you're stating your truth as you know it then, just like we all are. Replacements are a optional one time occurrence and then it's OK I'm sorry sir/madame, but it's clearly not working here, you're going to need to source your eggs somewhere else. As others have stated, some people you aren't going to satisfy. If they are still unhappy after your replacement, then there isn't anything you can do about that. You've gone above and beyond. If they are nasty to you, you can block them from buying from you again, but I only do that if things go south, like a negative reputation, comment, something like that.