Britain’s information regulator said on Wednesday it had fined Carphone Warehouse 400,000 pounds ($539,400) after a 2015 cyber attack exposed the personal data of more than 3 million customers.


The Information Commissioner said the fine was one of the biggest it had issued after the electrical goods and mobile phone retailer failed to secure its systems.


The compromised personal data included names, addresses, phone numbers, dates of birth, marital status and, for more than 18,000 customers, their historical payment card details.