It was reported that 100,000 suppliers of Bulldog had their personal credit card details distributed to marketing networks.
However, Cable and Wireless is maintaining that there is still no evidence to suggest that the information was taken in breach and the telco cannot determine what was exactly taken.
Bulldog customers have been receiving numerous unsolicited marketing calls sparking a high number of complaints. Cable and Wireless are at the centre of the argument because they owned it at the time.
Cable and Wireless said: "We are already taking appropriate legal action against the third parties that we believe may be responsible for this unauthorised use of our customer data." It appealed for Bulldog customers who think they might have been affected to get in touch to assist with legal proceedings.
Pipex meanwhile said: "Our understanding is that following an external enquiry by Cable and Wireless it has become apparent that at some point in December 2005 Cable and Wireless had some of their customer contact details illegally obtained."