Rail companies are failing to tell passengers that they are now entitled to refunds for problems such as overcrowding and dirty toilets.
On Saturday, the Consumer Rights Act was extended to cover rail, coach and ferry companies, following a campaign by Which?. The transport sector had been claiming that doing this could increase industry costs by up to £3.5 billion per year - but a government analysis indicated that this simply wasn't the case.
Now, customers are entitled to a refund not just for delays, cancellation and denied boarding, but also for a journey that's been provided 'without reasonable care and skill'.
They can even claim for extra expenses incurred because of delays of half an hour or more.
However, despite the change, the Sunday Telegraph has discovered, three quarters of rail companies have failed to update their websites to include the change.
For example, Great Western Railway's website still reads: "If your train is delayed or cancelled, we won't give you compensation for any losses or extra costs (if you miss a plane, for example)."
Louise Ellman, the Labour chairman of the Transport Select Committee, says the companies should have taken action immediately to change their terms and conditions.
"This is disgraceful," she says. "Passengers have been demanding change and the train operators must deliver on their promises."
Under the new regulations, compensation must be paid within 14 days, and will be made by the same method the passenger paid with, rather than with the vouchers that some train companies currently use.
However, claiming compensation may not all be plain sailing, according to William Spickett, a principal associate at law firm Eversheds.
"A passenger seeking full compensation would need to demonstrate that the operator had not acted with reasonable skill and care in providing the services and that as a result the passenger had suffered a loss up to the value of the price paid," he says.
"Given that many consumer groups already point out that passengers find existing methods of seeking compensation too difficult, complex or time consuming, it is questionable whether significant numbers of passengers would have the appetite or the awareness to pursue a claim before the courts."
Which? has a free tool on its website designed to help you claim compensation, here.