If someone has posted something negative about your company, it is visible to that person, people in their social media network or anyone searching for information about your company. By not responding to a negative comment, a small negative comment can grow into a huge public relations issue. In fact, many legitimate review sites give more weight to how a company handles negative reviews vs positive reviews.
Your company should admit mistakes when necessary and share with the person how your company is going to address the issues. Remember “it’s just business”. A simple response can actually turn an angry commenter into a product or brand evangelist and promote your business in a positive way.