Online payment operator WorldPay is still struggling to keep its business operational four days after a massive denial of service attack first clogged up its systems and suspended services for merchant customers.
The company, which is owned by the Royal Bank of Scotland, has initiated measures to restore services to some customers, but says that it continues to face sporadic attacks and that its systems staff are still engaged in fire-fighting.
Cambridge-based WorldPay says it has engaged the UK's National Hi-Tech Crime Unit in an effort to track down the individuals behind the attack.
The ongoing failure to restore full services to WorldPay's 27,000 merchant customers could prove costly to the firm as the busy Christmas shopping season approaches. WorldPay has said that it will discuss compensation with individual merchants prevented from doing business online on a case-by-case basis.
Rival operators such as Netbank have moved to exploit WorldPay's discomfort, offering "emergency services" to customers disrupted by the attack.