This happened to me last year. I went to a dentist near by where I moved. The dentist and her assistant were both highly incompetent. Her assistant for example, could not understand a single word. When I demanded my X-rays, so that I can go and get a second opinion, I was refused at first and then told that it will cost $25.

So, I went to Yelp and put a review about them. To my surprise, I received a call from them asking to remove the review or I'll face lawsuit. I deleted the review.

To be honest, the language I had used was not bad in any way and all I did was describe my ordeal with an incompetent doctor.