Rail user groups are fighting plans to reduce ticket office opening hours by South Eastern Trains.
The rail operator said staff could be more productively employed
The rail operator has put forward proposals to cut about 100 jobs at stations in London and the South East.
A spokesman said ticket sale patterns had changed and 90 jobs would be created, and redeployment offered.
Rail Passengers Committees said on Wednesday passengers needed more advice not less. They want people to write to the rail operator to oppose the plans.
Mark Woodbridge, regional director for the Rail Passengers Committee Southern England, said the rail firm had not shown the benefits to passengers.
'Not the answer'
"Passengers do not like stations unmanned - they prefer the human touch and a perception that someone is in control and looking after their welfare," he said.
"Replacing people with machines is not the way forward as they do not offer the full range of tickets and cannot provide the human interface that passengers demand."
Brian Cooke, chairman of the London Transport Users' Committee, said: "This is one of the daftest proposals we have seen from a train operator at a time when train travel is increasing and passengers are faced with an increasingly complex ticketing range.
"Replacing ticket office with more staff on trains is not the answer."
'Consultation under way'
When the plans were announced, the rail operator said ticket office staff could be more productively employed at quiet times and new jobs would improve security, station presentation and revenue protection.
A spokesman said new ticket vending machines were being installed at stations which could issue a full range of tickets and take credit cards, so passengers could buy tickets when offices were unstaffed.
He added proposals were not yet final and consultation was under way with rail industry watchdogs.
South Eastern Trains (SET) took over rail services between London and Kent and Sussex after Connex lost the regional franchise.