A public consultation on plans to shut the ticket offices at Rotherhithe and Surrey Quays Station is currently under way.
The plans have been submitted by Arriva Rail London, the company which runs the London Overground concession for Transport for London.
ARL says that it is proposals include making staff more visible and available at stations, providing assistance and information where it is most needed, and modernising the process for selling tickets to reflect changes in how people are paying for their travel.
As part of this, it is now consulting with rail industry bodies and London TravelWatch about closing ticket offices at 51 stations where there are fewer than 12 ticket sales per hour.
The ticket offices at Rotherhithe and Surrey Quays are already only open for 15 hours a week (weekdays 7am-10am).
London TravelWatch (LTW) is seeking views on the ticket office proposals from passengers and stakeholders on its website until Thursday 11 October 2018 so that they can be taken into account before any decisions are made.
RMT union general secretary Mick Cash said: “I am calling on Mayor of London Sadiq Khan to oppose this retrograde plan for wholesale closures in the strongest possible terms. Ticket offices play a crucial role at train stations.
“London needs to welcome its passengers, visitors and tourists not with a machine, but a welcoming and friendly ticket office who can provide a full range of services.
“This is just the latest attack on a properly staffed, safe, secure and accessible railway for all and RMT is determined to halt these plans in their tracks.”