There are many out there who prey on the innocence, ignorance, or desperation of those who are in need of immigration services. Often people are duped in paying for thousands of dollars by "notarios", and "immigration consultants".
“The word notario in the Hispanic community has a completely different meaning than it has in the United States,” says the incoming president of the American Bar Association. "In many countries, a notario is not just the same thing as an American notary public, but the moniker can also denote someone authorized to handle a variety of legal matters."
According to an article in the Daily Business Review (link)
"An April indictment charged three Miami residents who allegedly held themselves out as immigration consultants; one said he was a Homeland Security agent who could help with documents. Ripping off the valid immigration numbers of identity theft victims from Mexico, Poland, Ethiopia and Jamaica, the team allegedly collected $425,000, charging immigrants in Miami and New York as much as $7,500 each to process Internet applications for visas. Two defendants pleaded guilty and one was convicted at trial. They face sentences of up to 25 years in federal prison."
The USCIS has this posted this informative page on their official website to help people find the necessary legal help. Link.