Residential, small business and ex-customers
All residential, small business and ex-customers' data is stored in the same system so if they have managed to get one set of data they will have probably obtained all as it would actually be easier, once in, to take everything than to identify specific accounts.
I wonder if the government will be doing anything about companies holding (and losing) the data of people they don't even provide services for anymore. Oh noooo... Dido is married to one of Mr Cameron's friends in government. What are the odds, a guy is a member of the party that leads the country, and his wife gets offered a job to lead one of the biggest communications companies in that very same country. Some people get all the 'luck'.