Fury and Frustration Over Target Data Breach Potential victims of credit card fraud tied to Target's security breach said they had trouble contacting the discounter through its website and call centers. Angry Target customers expressed their displeasure in comments on the company's Facebook page. Some even threatened to stop shopping at the store. Target apologized on Facebook and said it's working hard to resolve the problem and is adding more workers to field calls and help solve website issues. The fury and frustration come as the nation's second-largest discounter acknowledged Thursday that data connected to about 40 million credit and debit card accounts was stolen as part of a breach that began over the Thanksgiving weekend. The theft is the second-largest credit card breach in U.S. history, exceeded only by a scam that began in 2005 involving retailer TJX Cos. That incident affected at least 45.7 million card users. Target disclosed the theft a day after reports that the company was investigating a breach. The retailer's data-security troubles and its ensuing public relations nightmare threaten to drive off holiday shoppers during the company's busiest time of year. Christopher Browning, of Chesterfield, Va., said he was the victim of credit card fraud earlier this week and believes it was tied to a purchase he made at Target with his Visa card on Black Friday. When he called Visa on Thursday, the card issuer could not confirm his suspicions. He said he hasn't been able to get through to Target's call center. On Monday, Browning received a call from his bank's anti-fraud unit saying there were two attempts to use his credit card in California - one at a casino in Tracey, Calif., for $8,000 and the other at a casino in Pacheco, for $3,000. Both occurred on Sunday and both were denied. He canceled his credit card and plans to use cash. "I won't shop at Target again until the people behind this theft are caught or the reasons for the breach are identified and fixed," he said. The stolen data included customer names, credit and debit card numbers, card expiration dates and the embedded code on the magnetic strip found on the backs of cards, Target said. There was no indication the three- or four-digit security numbers visible on the back of the card were affected, Target said. Target hasn't disclosed exactly how the breach occurred but said it has fixed the problem. Given the millions of dollars that company's such as Target spend implementing credit-card security measures each year, Avivah Litan, a security analyst with Gartner Research said she believes the theft may have been an inside job. Other experts theorize that Target's network was hacked and infiltrated from the outside. Whatever the case, Jason Oxman, CEO of the Electronics Transaction Association, which represents the payments technology industry, said data breaches like Target's are generally "heavily organized and sophisticated."