CNet reports on hearings scheduled to open tomorrow in the US Senate on mysterious charges on thousands of consumers' credit cards. The Senate Committee on Commerce, Science and Transportation has been investigating online loyalty programs, which shoppers encounter (often with little comprehension) on the sites of online retailers such as as Continental Airlines, FTD, and Classmates.com. "At the center of the federal probe are Webloyalty, Affinion, and Vertrue, companies that make 'cash-back' and coupon offers to consumers and charge them monthly fees to enroll in their loyalty programs. ... In August, as the government's investigation rolled on, Webloyalty announced that it would alter its ads to require that consumers 'enter the last four digits of their credit or debit card to confirm' they wish to pay the membership fees. Last week, Affinion made similar changes. During the hearing, when the Senate committee is expected to make public the results of a six-month investigation, it will also likely say the alterations made by Webloyalty and Affinion don't go far enough. "