Travel disruption and overcrowding at London Bridge because of rebuilding work has been criticised by government minister Michael Fallon.
The station is being rebuilt as part of the £6.5bn Thameslink Programme.
The Conservative MP for Sevenoaks said there had been “too much disruption” and some serious overcrowding”.
Network Rail admitted recent problems, as a result of work on the north side platforms, were “unacceptable” and “embarrassing”.
“We all want to see London Bridge rebuilt but they have been planning this for a long time now,” Mr Fallon said.
“These are works that are going to go on for the next two years and therefore it is important that they get it right, that we don’t have overcrowded platforms and people have proper information and they are told clearly what their alternative routes are.
“It is not yet working well.”
Charing Cross services, which stopped calling at London Bridge on 12 January, are due to resume in August 2016.
Mr Fallon added: “This is week two. I’ve asked the managing director of Southeastern to travel up from Sevenoaks in the morning, as a commuter, and to come down in the evening at the peak hour to see how we can better manage the flow of people at London Bridge.”
He said he would like to see more staff helping commuters and also urged Southeastern to allow people to use their tickets at more stations.
Network Rail apologised to passengers for major disruption 10 days ago when a new timetable was introduced for Southern and Thameslink trains at London Bridge.
The company said it was reviewing services and had made changes to ease crowding on the station concourse, including new customer information screens and more staff.
It also apologised for reliability problems with equipment on the railway near London Bridge, which caused further delays over the last week.
At 178 years old, London Bridge is the city’s oldest surviving rail terminus.
The new concourse at the station will increase passenger capacity by 65% when complete, according to Network Rail.
A Southeastern spokesman said David Statham, the rail company’s managing director, had been travelling across the network since the new timetable was introduced on 12 January.
“He met with Mr Fallon last Friday and welcomed the invitation to travel from Sevenoaks as part of his tour of the network,” the spokesman said.
“Southeastern is closely monitoring the feedback from passengers.”