Train companies are encouraging people to switch to e-tickets on the grounds that they are more convenient and better for the environment. But the case of a 72-year-old woman, who bought an e-ticket for her journey but was later threatened with prosecution in the magistrates court for alleged fare-dodging, may send some scurrying back to paper.

When you buy an e-ticket, it is emailed. On the train you show your smartphone – or a print-out of the ticket – to the inspector, who scans the barcode. But if a print-out is OK, then surely a screenshot is, too?

Pat Hendricks* claims she was treated as if she was a criminal after she used a screenshot of her ticket’s barcode to gain access to the platform and board a train.

Her case, which the passenger watchdog Transport Focus says showed an “astonishing contempt for fare-paying passengers”, arguably makes a mockery of rail industry claims that it wants to bring ticketing into the 21st century.

It also reveals how the train companies use unregulated private companies to pursue passengers with “menacing” letters seemingly designed to frighten recipients into handing over large sums of money.

Hendricks says staff at Bristol Temple Meads station had no problem with a screenshot of her e-ticket when she arrived to take a train to Manchester in April. (She had bought her ticket the previous month.) They allowed her to enter the station’s platform.

At that point she discovered the through train she had booked had been cancelled, and she would have to get another train that involved changing at Birmingham.

Everything was also fine when the inspector on the train to Birmingham checked her barcode. On her screenshot, it was partially obscured by the ringtone bar, though both staff members confirmed that enough of the code was visible to validate it. But on the second leg of the journey, from Birmingham to Manchester, the “officious” inspector refused to accept the screenshot saying it was “not valid”.

“I could tell that she was going to be as difficult as possible, and she flatly refused to accept it,” says Hendricks. “I showed her the first booking email as proof, but for some reason couldn’t find the ticket email – though I’m not sure she would have accepted it anyway,” adds the retired woman, who lives just outside Bristol.

What happened next left her, she says, feeling “very badly abused by the system”. A private company, Transport Investigations Limited, acting on behalf of train company CrossCountry, informed her that “sufficient evidence does exist to warrant a prosecution”. Her file, the letter stated, was with the prosecutions team, “who are considering whether to issue a summons” at the magistrates court.

Hendricks pointed out she had bought a ticket, and sent evidence.

“I assumed that would be the end of it. But instead of an apology, demands became even more menacing.” A second letter alleged she had boarded a train “with the intention of travelling without having previously paid the correct amount”. Says Hendricks: “It was also suggested that a more serious charge of ‘intent to avoid a fare’ could be considered. It offered to end the matter if I paid £161.30.”

After much deliberation she decided to pay, as it would have cost more in legal fees to fight.

“It felt completely wrong, as though I had been treated like a criminal … I am lucky I could afford to pay it. For others on low incomes it could have been a financial disaster,” she says.

Anthony Smith, who runs Transport Focus, which represents passengers, says the case suggests an “astonishing contempt for fare-paying passengers”, given there was clearly no intention to defraud the railway. “We are pushing for a change of legislation in this area, which may well happen this year,” he says. “Prosecution should only be threatened if there is clear intent to defraud.” He described the tone of Transport Investigations’ letters as “extraordinary”.

CrossCountry admitted the episode had not been the firm’s finest hour, but then claimed that the inspector and Transport Investigations had been correct, as the passenger did not have a “valid” ticket. “The terms and conditions of e-tickets are clear that the customer must activate and take the ticket with them when they travel. A photograph or screenshot is not acceptable, as this is not the ticket and could be used by anyone.

“However, we had already let this customer down before it got to that point. The train was cancelled because of a points failure, and staff at Bristol should not have let her on to the station platform after being shown the photo instead of a ticket.”

The company has agreed to refund Hendricks the £161, and has brought the matter to a close. Transport Investigations declined to respond, despite repeated requests. Guardian Money has been told the wording of the letters sent to Hendricks is “under review”.

Her case will leave many unclear about the use of screenshots. The CrossCountry website says: “You can show your ticket via your Apple Wallet, as a pdf on your phone, print it at home, or open it in the CrossCountry Train Tickets app, the choice is yours!”

Meanwhile, one of the Transport Investigations letters says: “A photo of a ticket is not a valid ticket held.”

Yet the Rail Delivery Group (RDG), which is responsible for ticketing across the UK network, initially told Money that passengers can use screenshots of QR barcodes, as used daily by people taking flights. They have the advantage of being easily accessed even if the phone handset has no signal or has run out of data.

The RDG later confirmed that screenshots of tickets may be accepted as valid tickets if the barcode can be validated by an inspector using a scanner, but it said this is not recommended as it increases the chances of the ticket becoming obscured and unreadable.

RDG says: “When a customer receives a smart ticket, they are provided with guidance on how to use it, and we are improving staff training to help ensure customers receive a consistent service across the network as we increase the availability of smart tickets to better reflect how people live and work.”

That is not enough for Hendricks. “I certainly won’t be bothering with e-tickets – why would anyone want the hassle of going through all that?” she says. “It’s back to paper for me.”

*Not her real name