Shoppers took to social media to share that yellow sticker items were scanning at full price on self-service tills at Sainsbury's stores, and to get the discount, they had to call over a Sainsbury's staff member to approve it

The supermarket giant, which is rivalled by Tesco, Morrisons, Asda, Lidl and Aldi, wants to clamp down on fake discount coupons is causing friction at self-service checkouts.