Online banking services and automatic teller machines (ATMs) provided by Hong Kong’s largest bank HSBC and its subsidiary Hang Seng Bank broke down on Sunday, leaving millions of customers in the city unable to access their accounts. Account-holders with HSBC complained that its online banking app was out of service, while several others said they could not withdraw money from its ATMs at around noon. Several Hang Seng customers said they were also unable to access online banking services, with a message appearing on the screen stating: “We are not able to process your instruction.” Hongkongers have been unable to…