The data protection watchdog has served Carphone Warehouse and Talk Talk with enforcement notices

The Information Commissioner's Office has found two firms, the Carphone Warehouse and sister company Talk Talk, in breach of the data protection act. The ICO said today that it had ordered the firms to improve the way that they manage and store their customers' personal data.

The warning follows an ICO investigation that found that the firms were improperly handling data, in some cases opening customer accounts in the wrong name, and in others by passing the wrong customer information over to agencies for credit checks. Other failings meant that customers would be able to see other customer account details online.

The ICO also said that neither firm had adequately responded to customer requests for access to data that the firms held about them. As a result it has served both with an enforcement notice which orders them to comply with the Act. Failure to comply with the notice is a criminal act, the ICO warned.

In a statement announcing the action Mick Gorrill, assistant commissioner, warned other firms that the ICO would continue to investigate, and prosecute firms, where necessary.

"The Data Protection Act gives us all important rights, including the right to correct inaccurate information and to find out what information an organization holds on us. Organisations that process personal information must comply with the Act and, where we find that this is not the case, the ICO will take enforcement action."