I've noticed this on the NXEA website:
National Express is committed to ensuring all customers have paid the fare for the journey they are making. If you believe a fellow customer is deliberately avoiding payment of their fare you can text the details to 60006. Please start your message with the word dodger and provide us with details of the train you are travelling on, where you are travelling from and destination, the carriage and a few details of what the person looks like. For example: 1600 London - Norwich Coach J Tall person. All information will be treated in the strictest confidence.
http://www.nationalexpresseastanglia.com/tickets-fares/ticket-information/penalty-fares--1
National Express is committed to ensuring all customers have paid the fare for the journey they are making. If you believe a fellow customer is deliberately avoiding payment of their fare you can text the details to 60006. Please start your message with the word dodger and provide us with details of the train you are travelling on, where you are travelling from and destination, the carriage and a few details of what the person looks like. For example: 1600 London - Norwich Coach J Tall person. All information will be treated in the strictest confidence.
http://www.nationalexpresseastanglia.com/tickets-fares/ticket-information/penalty-fares--1