I can only recommend that you be as polite/gentle as possible, but don't sugar coat it. Let them know you're glad you got your little baby, but she's extremely weak and malnourished and will require specialized care if she's expected to make a full recovery. I would definitely express concern for any other balls that remain in their care, and advise them to critically look at their husbandry practices. If need be, get those other little ones medical attention ASAP. Just my .02