It is a criminal offence for traders to deliberately make misleading price claims about their goods or services and against the letter of the law to make prices confusing to the consumer.
For example, 'was £120, now £99.99' is deceiving if the goods or services have never been presented at the higher price. It is also misleading/confusing if a trader fails to show 'hidden extras', or to make it clear when a price is conditional on, say, another purchase.