Train customers have expressed their anger at being unable to get refunds for tickets they can no longer use because of UK coronavirus restrictions.
In some parts of the UK, people have been advised against all but essential travel after a spike in Covid-19 cases.
However, passengers who bought advance tickets to travel to or from these areas are not entitled to refunds.
The passenger watchdog said customers shouldn't be left "out of pocket for doing the right thing".
Advance tickets are usually non-refundable, although those restrictions were temporarily relaxed when the UK went into a nationwide lockdown in March.
UK train companies have been propped up during the pandemic by money from the government, which has set the advance ticket policy.
The Department for Transport said it was focusing investment "on maintaining services" to "ensure we are fair to taxpayers".
Lola Mitchell, 41, from Brighton, said it was "unbelievable" she hadn't been able to get a refund for her £106.50 tickets for a return journey from London to Newcastle.
She was due to travel to the North East last month for a socially-distanced concert, which was cancelled when new restrictions were introduced in Newcastle on 17 September.
Those measures included advising people in the area to only use public transport for essential purposes.
Lola cancelled her trip and has been trying to get her money back from LNER for her advance tickets, which are sold as non-refundable.
She was offered the option of changing her date of travel for a £10 fee before her scheduled departure - but not a refund.
The government-owned train company has told customers that the Department for Transport has told it that "normal ticket restrictions are still to be upheld" despite the local lockdowns.
Lola said that the day before her planned travel date, LNER emailed her to ask her to consider whether making her journey was essential.
"What a wind-up, if they are not prepared to offer a refund," she said.
Aaron, from London, had also planned a trip to Newcastle with his girlfriend. They were going to celebrate their first anniversary and had booked their train tickets "months before the restrictions came in" for the first weekend in October.
He says he was "shocked" when LNER wouldn't refund his "non-essential journey", and instead told him to choose another time, for a £10 admin fee - although LNER currently only sells tickets up until November.
That isn't an option for him, he says, because "who knows if they'll be out of lockdown - and secondly I have no reason to travel to Newcastle any more".
'I can't win'
Another rail customer, Sue Taylor, 46, who lives in Fulham in London, was planning on staying with friends in Glasgow. She had bought a £33 advance ticket with Avanti for the return journey to London at the end of October.
Last month indoor visits between households were banned, first in Glasgow, and then extended to the rest of Scotland, until further notice.
The train companies will allow customers to change their advance tickets to a different day for a £10 administration fee, although Avanti has only released tickets until mid-December.
Sue said she would settle for a credit note, or the ability to be able to change the date of the ticket without a charge.
"As it stands the only options I have are to either lose the ticket or pay another £10 to change, to a date of who knows when. So much uncertainty.
"Do I change it now for £10, only to have that date become unworkable and have to pay another £10 to change again? There's no winning for me."
She added: "I do understand that the advance single ticket is, under normal circumstances, non-refundable, but we know nothing about the current situation is normal."
Another train company offering long-distance travel across the UK, CrossCountry Trains, doesn't charge the £10 admin fee - although that was a policy it introduced before the coronavirus outbreak.
Anthony Smith, chief executive of independent passenger watchdog Transport Focus, said: "Passengers no longer able to travel because of local lockdowns shouldn't be out of pocket for doing the right thing.
"If they are asked not to travel, it seems unfair that they will lose the money for pre-booked journeys.
"While the government continues to provide high levels of support to make sure the day to day railway keeps operating, advance tickets must be made more flexible or the railway will lose both custom and goodwill."
The Rail Delivery Group, which represents train operators, said the government initially offered refunds on advance tickets "due to the exceptional circumstances the country faced".
A spokesman added: "Significant taxpayer funding continues to help maintain rail services which is supporting the country's recovery from the pandemic and, after careful consideration, the government does not intend to allow refunds for non-refundable advance tickets."
A Department for Transport spokeswoman said the government took immediate action at the outbreak of the pandemic to support the rail industry and delivered "refunds on all advance fares, as well as removing charges for cancellations".
She added: "With fares revenue having fallen to less than 5% of pre-Covid levels, we must ensure we are fair to taxpayers and focus investment on maintaining services, to enable social distancing and support our economic recovery."