Vital improvements to the Tube are months behind schedule, according to figures from Transport for London.
The number of lifts and escalators for renewal has been "revised down"
A report shows just 10 out of 18 stations set to be refurbished by the end of the month are finished.
The London Assembly Transport Committee is due to discuss the repairs later this week.
Metronet and Tube Lines took over responsibility for maintenance under the Public Private Partnership (PPP) scheme in 2003.
The firms have 30-year contracts worth £15bn and combined profits of almost £100m.
In the first seven years of the 30-year PPP contracts a third of the tracks are meant to be replaced but two years into the programme, only 4% of track has been replaced.
The number of lifts and escalators planned for renewal has been "revised down" from 58% to 44%.
Transport union RMT's general secretary Bob Crow is calling for an end to PPP.
"The only winners from the PPP are the contractors who are pocketing £2m a week in profits at our expense," he said.
"Several reports have already shown that privatising work on the Tube infrastructure has brought nothing but delays, excuses and increasing safety concerns."
Roger Evans, deputy chairman of the transport committee said: "Obviously this is a 30-year contract so there is time to make up ground but it's very important we catch these things early.
"There is a lot of money going into this and Londoners expect results."
Tube Lines, in charge of rebuilding the Jubilee, Northern and Piccadilly Lines said the figures "misrepresented the picture" of their "true performance".
"With four times the amount of work now ongoing since we started two years ago on our three lines we are making real progress in delivering the upgrades to the Tube that Londoners expect.
'Ahead of schedule'
"Tube Lines is ahead of its plans to deliver increased investment to London Underground and is running to agreed schedule."
Metronet said it was ahead of schedule in laying new track.
"In all, improvement works to 45 stations are expected to have either been completed or commenced by the end of 2005," a spokeswoman said.
"Modernisation work to one of the largest stations, Oxford Circus, was started in November 2004 with the £55m project due for completion in 2008."