Waitrose has promised to add "common sense" ­features to its problem-plagued online delivery site admitting that the platform was not built to remember shopper addresses or their local branches.

New users currently have to complete an online registration form that asks for personal details, but the site fails to retrieve a lot of this information when customers return.

Waitrose is now working to put this right and has published a statement on its official online forum saying it will run updates over coming months to ­ensure the site stores and retrieves postcodes and ­local branches. It will also store delivery and billing addresses.

"These are common sense features," said an online retail expert, adding that their absence was "symptomatic of building a site from the technology up rather than thinking of customer needs first."

Waitrose has been dogged by complaints since the site launched five months ago. In its latest update last weekend, it also promised to continue work on improving the search facility and the way products are grouped. But shoppers remain unimpressed and continue to post complaints daily on the Our Website section of the Waitrose forum.

Among negative comments last week about the speed and usability of the site, two users said they were unable to buy nappies. Waitrose replied: "We are experiencing an issue with our system whereby many baby products are not available for some ­customers."

The supermarket defended its site, arguing that social media and ­forums magnified discontent and that the number of people posting on its forum was only a small fraction of the customer base. It added that orders were now up 31% on last year.