Thousands of Web shoppers have complained that "mystery charges" are showing up on their credit card statements and have accused those who operate so-called Web loyalty programs of duping them into signing up.

As a result, the U.S. Senate Commerce Committee is investigating Vertrue, WebLoyalty, and Affinion--companies who make "cash-back" and coupon offers to consumers and charge those who enroll in their loyalty programs.

Apparently, many consumers are unaware that for years now, e-tailers such as Buy.com, Orbitz, Fandango, and hundreds of others have given Web loyalty programs, also known as post-transaction marketers, access to their customers' credit cards. Some online shoppers don't realize that when they enter their e-mail addresses into these ads, they are opting into the programs and authorizing the charges.

Representatives from Buy.com, Orbtiz and Fandango say they are doing their customers a favor.

A spokeswoman for the U.S. Senate Commerce Committee told CNET on Wednesday that what started as a preliminary inquiry into WebLoyalty, Vertrue, and Affinion is now a "full-blown" investigation. She said: "It's becoming clearer and clearer that consumers can be at risk for these mystery charges when they shop online."

http://news.cnet.com/8301-1023_3-10293633-93.html