Outdated promotions
How many times have you found items at great prices only to get to the register and pay a completely different amount? Unfortunately, this is a common practice in many supermarkets.
Whether intentionally or simply due to bad management, most stores don’t keep their displays up to date and still display promotional prices that are no longer valid. The result is that customers get overcharged instead of paying less.
Therefore, always make sure the promotion has been deducted when you paid at the register and if not, show the display to a manager and ask for a refund.