I'm sure I read on here somewhere that if a special offer has less than a week to run, and is out of stock, you can be issued with a voucher to allow you to buy it at that price when it's back in stock. However I was in Asda on saturday, looking for some £5 packs of 20 carlsbergs. The shelf was empty, so I asked at customer services, who in turn asked the duty manager, who didn't know what I was talking about. Luckily for me, an employee queueing to have her lottery ticket checked mentioned that she had seen some out the back, (probably put aside by staff), so the helpful duty manager went out and got me two boxes! Was I right though?