Article 21U.K.Liability for booking errors
Member States shall ensure that a trader is liable for any errors due to technical defects in the booking system which are attributable to him and, where the trader has agreed to arrange the booking of a package or of travel services which are part of linked travel arrangements, for the errors made during the booking process.
A trader shall not be liable for booking errors which are attributable to the traveller or which are caused by unavoidable and extraordinary circumstances.