MPs have called for the Department for Transport to "get its house in order" after uncovering "basic errors" in the way it run the West Coast franchise competition.
The department was forced to reverse its decision to award the £5 billion franchise to FirstGroup last October after a legal challenge from rival bidder Virgin Group.
The latest report by the Public Accounts Committee finds that managers had no oversight in the bidding process and failed to respond to early warning signs that things were going wrong.
Committee chair Margaret Hodge said the competition would cost the taxpayer £50 million "at the very least".
More top news
Tech-giant given access to as many as 1.6 million UK patient files as part of a data-sharing agreement with the NHS, according to claims.
ITV News understands that the prime minister is preparing to make a major climbdown at PMQs on the issue of refugee children.
The parents of missing Madeleine McCann have said "there will always be hope" in the hunt for their daughter.