It is not unusual for a customer contacts us concerned with a case of bad reputation on the Internet, looking for a fast and thinking about SEO as an option to delete or remove locations where those results are read opinions that harm them.

Through SEO what we can achieve, rather than sink the pages with bad reviews, is to promote the company's own page, but still, positioning is not the only option to solve a problem of ill repute. In fact, we can turn a bad experience of a client in a positive, if we follow the following (inspired by this article ProvenSEO ):

Identifying the Problem
The first step is to identify the problem or grievance. Check if the complaint is legitimate and if we can do something to solve it.
It is clear that there is a possibility that the complaint is legitimate and that the case of negative propaganda by a rival company or simply someone looking to harm.

Humanizing the answer
A common mistake is to respond too defensive or just trying to eliminate the negative comments via threats or other means. 
It's much better to try to understand the origin of negative feedback. A response from calm and sympathetic to the injured party proves that you're listening to your customers. This would be a good example of how to turn negative into positive comments and look good with both current and potential customers.

Quick answer
is best answer as quickly as possible, showing that you care about your customers. Quick response minimizes the time to continue criticizing the commenter. Often a comment without response will follow angry commenter leaving more negative comments.

Play
is very well take the initiative and provide our customers a place to pour your views, whether good or bad. This allows us to respond quickly and minimize complaints and negative comments that they do elsewhere.

Conclusion
Before attacking or delete negative comments or received, you better think twice. We have a good opportunity to change things in our favor. 
Sometimes there are reasons to have received a bad comment, nobody is perfect. Once you have located the problem and after finding the solution, we will be able to prevent similar situations in the future.