An upcoming documentary describes Yelp as the internet's equivalent to the mafia, and the publicly-traded company is doing everything in its power to discredit the film before it is released. Yelp, founded in 2004 by two former PayPal employees, is a website that lets users write their own reviews of businesses like restaurants and doctor's offices. However, like many web businesses, Yelp's revenue comes mainly from advertising and the businesses that buy ads are often also rated and reviewed on the site. Kaylie Milliken is the filmmaker behind Billion Dollar Bully, an ongoing documentary focused on Yelp's impact on small businesses. While she hasn't finished the documentary yet, Milliken tells Daily Mail Online her research so far has indicated Yelp's advertising structure appears to punish businesses that choose not to advertise on the site - a claim that company has vigorously denied. Scroll down for video . A racket? A documentary filmmaker is currently working on a film about Yelp, which she says will unveil shady advertising practices at the company. Above, Yelp CEO Jeremy Stoppelman in August 2014 . Pay to play: Billion Dollar Bully is still in production, but filmmaker Kaylie Milliken says she's already interviewed several small businesses who believe they've been targeted by the company for refusing to advertise . 'Businesses feel extorted,' Milliken told Daily Mail Online. 'After they decline advertising services from Yelp they feel like their good reviews get filtered out and their negative reviews come to the front.' And at hundreds of dollars a month for advertising, the price to work with Yelp is too big for many mom and pop businesses, Milliken says. Milliken first started investigating the company a year ago, when she went to see her doctor, who started talking about her negative experiences being listed on Yelp. 'The more she talked about it, the more my jaw just kind of dropped. I knew that they had aggressive salespeople - my husband is a small -business owner and he’s complained before about how pushy they can be. But then she started telling me about receiving reviews, really negative reviews by clients, and she couldn’t figure out who these clients were. 'She was really upset over it. And then she received a review where the client listed ailments about themsel[f] that she had never seen before, and this was the day after she had gotten off the phone with someone from Yelp,' Milliken told International Business Times. Tense: Last month, filmmaker Milliken (right) appeared on CNBC to speak about the movie. Yelp spokeswoman Shannon Eis (left) also appeared on the show to defend the company . Last month, Milliken released a trailer for her documentary in an attempt to fund the rest of the film's production. The day after the trailer was released, Yelp stock dipped four per cent. Following the stock drop, Yelp issued a statement to Business Insider, fiercely denying the claims in the trailer. 'There is no merit to the claims they appear to highlight, which have been repeatedly dismissed by courts of law, investigated by government regulators, including the FTC, and disproven by academic study,' the company said. On the contrary, Yelp says its algorithm protects businesses, by weeding out potentially fraudulent posts seeking to boost a company's rating or drag it down. As a result, only about 75 per cent of posts are approved for posting on the site while the rest remain in a partially-hidden 'filtered reviews' section on each businesses' page. 'Because businesses have attempted to manipulate their ratings and those of their competitors by trying to post fake reviews, we have to protect consumers and honest businesses by preventing this behavior. As a result, Yelp has automated recommendation software in place to go through the more than 71 million reviews that have been submitted to Yelp to select the most useful and reliable content,' the company said in a statement to Daily Mail Online. Yelp's company spokesman Shannon Eis went on CNBC to speak out against the documentary in a segment with Milliken, to further illustrate how the company's business practices have been backed by both the courts and independent investigations. However, the Harvard Business School study that the Eis cited in Yelp's defense wasn't solely focused on whether advertising impacts the ratings of businesses listed on the site - rather the investigation was designed to find out how many of the reviews on the site were fake. While the study's authors did find that businesses that advertise on the site are no more likely to have extreme 1 or 5-star ratings than any other business, they made it clear that Yelp's advertising practices were not the topic of their study and therefore their research was not exhaustive. 'While our analysis provides some suggestive evidence against the theory that Yelp favors advertisers, we stress that it is neither exhaustive, nor conclusive. It is beyond the scope of this paper, and outside the capacity of our dataset to evaluate all the ways in which Yelp could favor advertisers,' the paper reads. Standing up: Milliken says that most of the business owners she spoke to were too afraid to appear on camera, for fear of retaliation fro Yelp. Pictured on the left interviewing a business owner, in a photo posted to her production company's website . Work to be done: The Kickstarter campaign to fund Milliken's project reached its $60,000 goal. She plans to resume filming in May and have a rough cut by fall . Milliken says she doesn't place much faith in these cases or investigations, after interviewing several small business owners in the course of her research. 'One company began to advertise with Yelp, but then stopped when their contract came up. The next month they went from five stars to four stars, and then three stars. That story is so common. It happens over and over again and a lot of businesses feel so frustrated at this point,' Milliken told Daily Mail Online. Milliken says that these business owners were so afraid of Yelp that about 80 per cent of them refused to go on camera for fear of retaliation on their own Yelp pages - which they are not allowed to opt out of. In their CNBC talk, Eis also accused Milliken of having a conflict of interest, since she had created several Yelp accounts to write fake reviews of businesses - including her husband's law practice. Milliken admitted to setting up the accounts, but said they were part of her research for the project. 'I think it's shocking and very telling that this billion dollar corporation has come after this grassroots production company - where there are only two of us - creating a documentary that were still in production over...and Yelp has fired back with all that...I think it does clearly show that they are concerned about what will be coming out in the documentary,' Milliken said on CNBC. Daily Mail Online reached out to Yelp for evidence of the allegedly fake reviews Milliken wrote, and the company sent screen grabs that show several accounts tied to the filmmaker and the fact that she commented on her husband's business page. While the 5-star reviews appear to be dated in 2011 (before Milliken says she started working on the documentary), Yelp did not provide copies of the actual reviews. Milliken says she reached out to Yelp for a sit-down interview, but that CEO Jeremy Stoppelman declined. In a statement, the company spokesman explained why they decided to pass on speaking to Milliken. 'Given that the title of the documentary already declares Yelp a bully before production and with a clear disregard for highly credible conclusions, we can be quite certain that our CEO's participation and any objective facts will not be fairly heard. We don't believe Mrs. Milliken is interested in the truth, considering she's shown such a disregard for it so far,' the statement reads. Prost Production's Kickstarter campaign reached its $60,000 funding goal, and Milliken says she will resume filming in May with plans to finish the project in fall so that she can submit it to the Sundance Film Festival.
Billion Dollar Bully, an upcoming documentary, focuses on the review site's impact on small businesses . Filmmaker Kaylie Milliken spoke to several business owners who believe their Yelp ratings went down after they declined to advertise on the site . The company has denied the allegations, citing court rulings, an FTC investigation and a Harvard study as validation of their business practices .