Don't panic. If someone is unhappy with your service, it's actually really good that you know about it. People are going to complain if they're unhappy, but if they're complaining in a place you can see, you have the opportunity to learn and remedy the situation if possible. Always reply to a negative review, and always start by thanking the person for taking time to write a review. Parents don't just consider other parents' reviews; they also want to see your grace and responsiveness in a difficult situation. This is actually an opportunity for you to demonstrate your excellent customer service skills. It's also a good reminder that you should be asking all your customers for feedback all the time. If you're doing a good job, and if your customers are writing reviews, your positive reviews will outweigh the negative ones.