Equifax Inc faced a storm of criticism yesterday over a hack that may have compromised personal data for some 143 million Americans. Consumers clamoured for answers and cyber security experts questioning the response to the massive breach.<br/><br/>Lawmakers and regulators joined the chorus, scrutinizing the company's follow-up as it encouraged potential victims to sign up for free credit monitoring services. Equifax shares tumbled as much as 18 percent, the biggest one-day drop in 16 years, as complaints mounted that the company's online and phone support systems were either broken or insufficient. <br/><br/>The hack, among the largest ever recorded, was especially alarming due to the richness of the information exposed, which included names, birthdays, addresses and Social Security and driver's licence numbers.<br/><br/>Responding to criticism, Equifax apologised for any inconvenience caused by its support website or call centre. It said the site is now functioning properly and that it had tripled the size of its call centre team to more than 2,000 agents, with more to be added.