I would not give a refund, she declined your offer for new eggs be done with her. Be sure to save all the conversations with her through screen shots, if she does try to bad mouth you, you will have your side of the story documented and any good egg chicken person will see she is totally trying...
I have limited experience with shipped eggs (I’m in the middle my first hatch right now) but my research I seen 7 hatched is awesome. Getting 6 Silkies for $45 is great, try buying quality chicks for that price. I don’t think you owe her anything, you sent extra. The only time I would complain...