Contractors working on a £500 million redevelopment of a major railway station have been accused of a "catalogue of faults" which have fuelled delays and disruption.
Passengers using London Bridge station in the capital have been subjected to overcrowding, late-running and cancelled services because of problems in recent weeks.
Labour MPs met with Transport Secretary Patrick McLoughlin, urging him to "get a grip" on the "failing management" at London Bridge station and to launch a "significant" compensation scheme for commuters affected by the disruption.
The Rail, Maritime and Transport (RMT) union said its officials had identified poorly-installed track and signalling layout, corners cut on quality of new points, Network Rail (NR) engineers left to correct contractor faults as well as "meaningless" computer models to justify the redevelopment plans.
General secretary Mick Cash said: "RMT warned from the off that the continuing chaos at London Bridge could be tracked back to the fragmentation and privatisation of our railways with its myriad of contractors and sub-contractors, and the drive to cut corners and rush through important works in the interest of meeting financial targets and protecting profits.
"The catalogue of faults identified by our reps is breath-taking and, alongside the abject failure to listen to our members who understand how a railway works, shows that the continuing chaos and overcrowding at London Bridge was entirely predictable.
"Even though RMT blew the whistle on this right from the off at no point since the pictures of the dangerous situation emerged have our reps and our members been asked for their views by the Department for Transport and the politicians who are posing about claiming that they are tackling the crisis.
"We were ignored at the start and we are still being ignored now, and our demand for a summit on the growing safety and overcrowding scandal on our transport services has fallen on deaf ears.
"RMT will continue to expose the truth while those responsible offer nothing but PR stunts and sticking plaster solutions."
Network Rail, and the train operators serving London Bridge, said they were taking action to make the station a better environment for passengers to use over the months ahead as rebuilding work continues.
Phil Hufton, NR's new managing director of network operations, said: "In the last few weeks passengers have experienced unacceptable levels of service and overcrowding at London Bridge station.
"Passengers have been very tolerant about the changes to their usual travel arrangements but understandably they have lost their patience with the recent poor service experienced, for which we are very sorry.
"The measures we are putting in place, in collaboration with our train operators, will improve both train service provision as well as station management in order that customers receive a better service at London Bridge and, if delays occur, they are given the help they need."
NR said the action plan included:
:: Increasing the number of staff on the station, particularly at peak times and at times of disruption.
:: Ensuring staff and passengers have access to the latest travel information and advice by boosting wi-fi capability, providing tablets to staff and bolstering information screens.
:: Better advanced warning for passengers of potential problems at the station, offering alternative travel advice enabling people to avoid the station at times of disruption.
:: Changes to the timetable to help a better flow of trains into, and out of, the station.
:: Reintroducing Olympic 2012-style "travel champions" and "customer action teams" who can be called upon to bolster station staffing levels and help people find their way.
Mr Hufton added: "I want to assure customers that we do take this situation seriously and Network Rail is committed to improving our performance by delivering improvements to deliver a safe environment for users of London Bridge hand in hand with meeting the level of train provision and customer service they rightly expect."
A Network Rail spokesman said: "Network Rail and its team of professional contractors are rebuilding London Bridge station.
"The current station is simply not up to the job required of it, which is why this transformation is essential.
"It's a huge, complex task, akin to building a football stadium while hosting a never-ending football match, but the team are working flat out to improve the management of the station and provide better information and conditions for passengers when the station gets busy.
"The team carried out a huge amount of work on the next stage of this rebuilding project in December and while some errors were found they were quickly fixed some months ago.
"Recent reliability problems are unconnected and are being thoroughly investigated to get to the root cause, make changes and ultimately improve equipment, and thus train reliability."