Egg has apologised to customers for its scrambled service but problems persist despite claims a fix was found last night.
The company said there had been a "hardware problem" which had taken some time to identify, and that "customer security had not been compromised at any time". However, Egg admitted normal service may not resume for two days.
Liz Gratton, director of customer experience, said: "We apologise unreservedly to those customers who have had difficulties in accessing their account online."
Customers have been unable to access personal account details on the site over the past four days but were in the dark as to why. No explanation was given on the home page. A customer services representative told vnunet.com that access to secure information was unavailable during a site upgrade to incorporate interactive television.
A customer told vnunet.com this afternoon how he "struggled to get from screen to screen, but I did eventually manage to get in to do a transfer". He described the site as "crawling". Egg says that problems still persist because of volume of traffic.
Gratton said: "We are confident that the fault is now fixed. The site is now very busy and there will be some congestion for the next few hours as we handle the volume, but we expect service to be back to normal within the next 48 hours."
On learning of the problems with the site, Gratton said Egg trebled capacity in its call centre to help customers service their accounts by phone.
Nick Jones, analyst with Jupiter MMXI, said: "The prime functionality of the site is to look at account details. The key thing is to communicate with users when problems occur. It is quite common to offer compensation but that can be more difficult with bank accounts."
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