Train passengers are facing fresh travel chaos after the RMT union announced that workers at Govia Thameslink Railway, including Southern, will strike on September 7 in protest at ticket office closures.
The strike will coincide with a walkout by RMT members on Southern in the long-running row over the role of guards.
The union is also in dispute with Southern's owner GTR, which also operates the Gatwick Express, Thameslink and Great Northern, over plans to close scores of ticket offices.
RMT general secretary Mick Cash said: "The Govia Thamelink franchise is in meltdown and not fit for purpose. Not content with axing catering services, closing ticket offices and attacking the role of their guards, they now want to threaten 130 station jobs and compromise the safety of both their passengers and staff alike.
"Our members have made it clear that they will not stand by while this basket-case franchise unleashes yet another attack on jobs and services in the drive for profits and that is why we have no option but to take strike action.
"These cuts plans fly in the face of the response from the thousands of passengers who objected to the closure of ticket offices and the de-staffing of stations as Govia drives on with plans for a 'faceless railway' where the public are left to fend for themselves on rammed-out, dangerous and unreliable services.
"It is about time Govia Thameslink started acting responsibly, halted their cuts plans and got round the table with the union in serious and genuine talks."
The announcement follows a 70% vote for strike action in a ballot of members.
GTR's proposed reorganisation of station staff would see the creation of a new role of Station Host, which the RMT said would lead to the closure of or reduced hours at 83 ticket offices.
A union statement said: "RMT is totally opposed to ticket office closures, and cuts in hours, as this will have a devastating impact on both staff and the safety and services offered to the travelling public. The latest proposals from the company will also result in a massive increase in lone working, including late at night.
"GTR are also totally ignoring the thousands of passengers who clearly indicated in our high-profile public campaign that they are appalled by the planned closure of ticket offices and the swingeing cuts to opening hours.
"They have failed to address the views of station staff and have ignored the objections from RMT and our sister rail unions. If these changes come in, the union believes it will mean all station staff could be forced on to flexible working with an increased workload."