I have been asked to reply on behalf of the Ministry of Justice.
The Data Protection Act (DPA) does not prevent Members of Parliament acting on behalf of their constituents regarding complaints to business and service providers. The DPA ensures that the handling of personal data, including disclosing it to third parties, is conducted in a lawful and proportionate manner, with appropriate safeguards in place. Given the principles-based nature of the legislation it is for organisations to decide in the context of their own operations how to apply the Act's requirements, within the limit of the law and available guidance.
The Information Commissioner's Office (ICO) provides extensive guidance on data protection for both organisations and the public, which can be accessed on its website: