Hackers were able to steal very sensitive information like Social Security and credit card account numbers. "Credit reporting agencies like Equifax make billions of dollars collecting and selling personal data about consumers without their consent, and then make consumers pay if they want to stop the sharing of their own data," Warren said in a statement. Freezing credit, which helps prevent identity thieves from wrecking a victim's credit score, costs between $2 and $10 depending on the state. There is also usually a fee to unfreeze credit. Equifax said earlier this week that it will waive the cost to freeze credit for the next month. Warren sent letters Friday to Equifax as well as its competitors TransUnion and Experian. She pushed to understand why the data breach occurred and how consumer information can be better protected.