Commuters on a busy London train route will no longer be able to travel using cheap-day return tickets during the evening rush hour.
First Capital Connect now runs the old Thameslink and WAGN routes
The restriction will apply to all First Capital Connect train trips from King's Cross, Moorgate and St Pancras stations between 1600 and 1900 BST.
The train operator said it hoped the measures, which begin on 11 June, would cut down on "chronic overcrowding".
They also affect one-day off-peak and family travel cards, and DaySave fares.
Geoff Pope, chairman of the London Assembly Transport Committee, said First Capital Connect's move was a money spinning scheme.
Until now First Capital Connect customers could buy cheap-day tickets for travel after 0930 BST and could return at any time.
The change means customers will have to pay £14.50 for a return journey rather than a cheap-day return of £7.90 if they want to go home during the evening peak times.
First Capital Connect managing director Elaine Holt said: "We realise that overcrowding is a major concern for our customers and we are looking at different ways of resolving this problem."
The firm says around 27% of cheap-day return ticket holders choose to travel between 1630 and 1900 BST.
Malcolm Ginsberg, who often travels between London and Potters Bar in Hertfordshire, said the move was "utterly contemptible".
"This latest scheme stops us from returning home when we want to," he said.
London TravelWatch chairman Brian Cooke described the changes as a "real dog's dinner".
He said: "While we accept that some trains are very crowded, this restriction certainly does not address that issue adequately or offer a long-term solution."
Mr Pope did not accept the operator's claim that the fare rises were to reduce overcrowding.
"The result will plainly be to increase their vast £176 million profits and that is why they are in business," he said.