Rail union leaders have urged the Government to halt plans by South West Trains - which operates services across the region - to reduce ticket office opening times, which they warned would lead to a "vastly poorer" service.
The Rail Maritime and Transport union said South West Trains should not be allowed to "slash" ticket office opening times.
A Government decision is expected soon on whether to allow cuts in hours at 114 stations that would leave some stations without ticket offices at weekends and dozens more without evening and early morning cover.
RMT general secretary Bob Crow said: "South West Trains passengers are already facing New Year increases in unregulated fares of more than 7 per cent, but the Government can act to stop ticket office cuts which would impose a vastly poorer service as well.
"The Government has the power to stop these unwarranted cuts and I have asked the minister to act decisively in the interests of passengers. Our campaign was endorsed by large numbers of passengers who were as horrified about the prospect as our members are.
"It is unacceptable that a hugely profitable company like SWT should attempt to lay off vital front line railway staff, not least in the current economic climate.
"We need to see more staff on stations, not fewer, but if SWT is allowed to get away with it, other greedy train operators will see it as a green light to shut ticket offices across the rail network."
SWT said it was still talking to the Transport Department and awaited a decision.
The firm said: "Ticket office opening hours at stations have not been reviewed for more than 10 years and with retail constantly evolving and peoples' needs changing there was a need to review this.
"The growth of sales from vending machines, internet and telesales led us to review ticket office sales, which in turn has led us to proposals to reduce the opening hours of ticket offices at 114 stations. There are no proposals to close any ticket offices. What the review identified are a number of stations where ticket office opening hours could be reduced."