WELWYN GARDEN CITY, England: Hackers broke into retailer Tesco's computers on October 22 and 23, causing the website to cease operating over the weekend.
Among the problems caused by the hackers included Tesco's grocery chain shutting down ordering on its website, and delivery tracking services also stopped operating.
Officials said that customer complaint began arriving at the start of the day on Oct 23.
Buyer complaints were continuous on Saturday and Sunday, as customers sought order cancellation details and refunds.
"There is no reason to believe that this issue impacts customer data, and we continue to take ongoing action to make sure all data stays safe," a company representative noted on Oct 24.
"Since yesterday, we've been experiencing disruption to our online grocery website and app. An attempt was made to interfere with our systems, which has caused problems with the search function on the site. We're working hard to fully restore all services and apologize for the inconvenience," the spokesperson added, as quoted by the BBC.