Rail passengers can challenge the amount of compensation they receive for delays and cancellations after strengthened rules to protect consumers took effect.
Travellers unhappy with the amount of their payout will be able to pursue a claim through the courts if they fail to resolve the issue with the train company.
The new power came into force on Saturday after the Government decided the Consumer Rights Act (CRA), introduced on October 1 last year, should apply to all transport services.
It means passengers are now able to claim compensation for problems beyond a delay.
The National Rail Conditions of Carriage have been updated to state that customers are entitled to receive cash rather than rail travel vouchers following disruption.
Passengers are generally entitled to a payout if they are delayed by at least half an hour, but the rules vary between train operators meaning some passengers are confused by how much money they can receive.
The Campaign for Better Transport (CBT) called for more clarity over what is covered by the CRA and how the Government and operators expect it to be applied.
It wants compensation for all delays over 15 minutes, automatic payouts when advance tickets are booked on train companies websites and compulsory on-train announcements when claims can be made.
Analysis by the Labour Party found that between 2010 and 2015 Network Rail paid train operators £575 million for delays and cancellations caused by issues such as signalling problems and power failures, while the rail firms paid just £73 million in compensation to passengers over the same period.
CBT's public transport campaigner, Lianna Etkind, said: "It's no wonder that so few passengers claim compensation at the moment. It's poorly publicised and the process is a hassle.
"Poor performance on the railways is not just limited to delays, and we welcome the fact that from this weekend, the new Consumer Rights Act will cover the quality of rail journeys as well.
"How much compensation will passengers be able to claim when the there is no working toilet on board, when there are no seats available or the promised wi-fi is not working? We will be working with passengers to press for answers so that more passengers to get proper redress when train companies let them down."
Jacqueline Starr, head of customer experience at the Rail Delivery Group, representing train operators and Network Rail, said: "Train companies' compensation arrangements already go beyond what is required under consumer law, and we want to give passengers an even better deal.
"We're making claiming compensation simpler and clearer, and we have tried to make the conditions of travel as simple and easy to understand as possible too.
"Passengers will be advised clearly of their right to compensation. Every train operator will comply with the Consumer Rights Act, including offering compensation by the method the passenger bought a ticket."