main COOK siteJust open your order at Your Account. COOK orders can be edited up to the 18th December or 2 full days before the order is due, whichever date is earlier.
If you have items in your basket, you'll be asked if you'd like to merge your order with those items or save them for later.
If you have promotions in your basket that are no longer available at the time of editing they will still be valid when you edit your order, unless you make a change to the items in your basket that are part of a deal.