Marks & Spencer has admitted that problems at its giant Leicestershire warehouse has led to customers suffering delays to their online orders.
The high street stalwart said a four-day period last month, which included "Black Friday" and "Cyber Monday", had proved very popular and prompted it to extend delivery times.
M&S's 900,000 sq ft warehouse in Castle Donington, which opened in May 2013, has been blamed for causing the problems.
A number of customers used M&S's Facebook page to complain, with one directly addressing chief executive Marc Bolland over a Christmas bauble order.
She said she was £100 out of pocket after taking time off work to await the delivery which was delayed by 48 hours despite her having paid extra for a specified date.
"I've two very disappointed small children who cannot wait to put up the tree.
"I'm forced to air my feelings as I am a lifelong M&S shopper. I would normally spend upwards of £500 over the Christmas period on presents, decorations, food and other things.
"I think I'm off to Aldi now on my day off. They don't do delivery, but neither do you."
M&S has struggled to get its new website up to speed since it was launched in February, blaming teething problems including issues with customer registration and navigation for a slump in sales in the first quarter.
Online sales were also down in the second quarter but not as badly as the previous period and M&S said last month they were on an improving trend and "on track to return to growth ahead of our peak trading period".
A spokesman said: "Our customer is always our top priority and that is why we've extended some of our delivery options.
"The vast majority of orders are delivered on time. If we do miss a delivery date, we will do all we can to rectify it for the customer."
