I believe a huge part of developing a strong brand image is connecting with customers. A major part of connecting with customers and building strong business customer relationships is not only ensuring their satisfaction with the product, but their satisfaction with the interactions they have when the they have issue with the product. A part of ensuring a positive customer experience is being personable with customers. If possible, I would reach out to the customer directly and understand why they had a negative experience that lead to their negative review. I would not come from a defensive position when responding to them, but try to best understand why their personal experience with the product/service was negative. I would then offer to send them an alternative product to try for free as an attempt to give them a second and more positive experience with the product.