Thousands of retailers worldwide are counting the cost of a hack attack that crippled internet payment company Worldpay for the better part of two days.
Starting early Tuesday, the company's payment and administration networks were flooded with computer-generated requests, clogging the system and slowing transactions - also known as a "denial-of-service" attack.
Worldpay, owned by the Royal Bank of Scotland Group, has taken steps to repel the attack, said Carolyn McAdam, a company spokeswoman. Some of the company's 27,000 clients, however, would have to wait until the end of Thursday for a normal service.
"It's a nightmare,'' said Jessica Gooch, director of Snorestore, an online retailer that sells earplugs for people blighted by noisy bedmates. "Customers will go elswhere."
Worldpay operates in more than 70 countries stretching from Australia to Sweden and accepts payments on credit cards including Visa, Mastercard, Diners and American Express. Clients range from heavyweights like Vodafone and Sony Music Entertainment to small online retailers.
Companies in the UK said the effects of the attack were amplified by last week's mail strike that delayed deliveries and payments in the lead up to Christmas, the busiest time of the year.
"I'd only just taken down the message telling customers that we were having problems with the mail strike," said Richard Selby, owner of Poisonmugs, which sells novelty chinaware and uses Worldpay to process customer payments.
"I make about 70% of annual sales in November and December."