Nearly a third of U.S. consumers have fallen for “negative option” scams – paying for shipping on a “free trial” or “sample,” and then unwittingly becoming victim to recurring credit card charges, according to Visa. The deceptive marketing practice has become so pervasive that Visa has joined the Federal Trade Commission and Better Business Bureau in warning the public to be vigilant when signing up for an online offer promoting free trials or samples.

The Federal Trade Commission said today it has sued to stop three companies that allegedly promised interest rate reductions on credit cards to consumers for upfront fees as high as $1,495 – but the companies delivered no such service. The three FTC complaints against Economic Relief Technologies; Dynamic Financial Group; and JPM Accelerated Services allege that “illegal pre-recorded robocalls” were made to consumers, using names such as “card services,” “credit card services” or “account services,” the FTC said.

The Federal Trade Commission, the nation’s consumer watchdog, would like social media users to help alert Christmas shoppers of credit scams and provide tips to protect cash, gift cards and private information. The FTC today made the “12 tweets of Christmas” available on its website.

Consumers – including military personnel and new immigrants – are increasingly falling prey to deceptive marketing practices by issuers of prepaid phone cards, the Federal Trade Commission told a House panel today. The FTC is seeking more legal muscle to crack down, via hefty judgements, against the prepaid card companies that promise many more minutes than their cards actually deliver.