A Long Beach, Calif., veterinarian has filed a federal class-action complaint against the online-review site Yelp, claiming it's a shakedown operation that will remove negative consumer reviews for cash.

Yelp's scam—it lets businesses manipulate their reviews if they pay $300 a month to advertise on Yelp.com—has garnered a good deal of coverage. But the company, which pulled in a reported $50 million last year, is now facing a class-action lawsuit from one business that refused to go along.

Gregory Perrault, who runs a veterinary practice called Cats and Dogs, says he started getting "frequent, high-pressure calls from Yelp advertising employees" after he contacted the company to ask them to remove an outdated review. For a yearly advertising commitment totaling $3,600, he was told, Yelp would push negative reviews to the bottom of its listing and make sure they don't get indexed by Google.

Perrault refused. Despite the fact that Cats and Dogs has an average four-star rating from Yelp users, the complaint says, its "tagline," or the first couple of words that show up in a search, says Perrault is the "most inept/rude veterinarian I have ever met."

A Yelp spokesman released a statement to the New York Times calling Perrault's allegations "demonstrably false, since many businesses that advertise on Yelp have both negative and positive reviews." You can read the complaint here.