What can we do with malicious online slander? It is not fair game!?

[Denise]

My husband and I own a small business, auto repair, and have been in same location for more than 21 years. Within the last year we have been trying to generate new business by heavily advertising. We noticed on some online sites, bad reviews on yelp and city search. In these reviews they mentioned how bad our service was and how they had to take took their cars to the local dealer , which is 3 blocks away. we have always had good reviews previously. In the last month we had a new client bring in her car for a service repair, she looked suspicious. Right after the repair this person posted information regarding her service experience about our business that was cruel. I know she had exceptional service because my husband personally helped her. She started the same day with her malicious blogging and social media bully reviews. This has been the most strenuous experience ever. She has complained about everything, from noises, A/C, starting problems, wrong parts, bad quality of parts, nothing was related to the repair and all lies. We asked her several times we would pick up her car or even go out to her house. She never returned a call she would just continue righting about us. She has gone to open blogs on face-book, bashing our company, reporting us to Triple A, reporting us to consumer protection and writing over 40 terrible reviews on different sites. This happened 3 months ago and continues these horrible reviews. Writing about me and my husband personally, discrediting us and judging our character. So much saying and questioning my second job as a realtor, which has nothing to do with anything. She has written GREAT things abut the dealer in the reviews, because she then took her car there. How can we stop this!! It's an outrage and SLANDER!!