Commuters have been stuck on trains for up to two hours on another day of rush-hour travel misery.
Delays, diversions and cancellations caused chaos to South West Trains (SWT) services, which were hit by signal failures at Surbiton in south west London and at Waterloo station in London.
On one packed train, passengers were forced to stand in the toilet because it was so full. Platforms at Surbiton and Woking were over-crowded.
Passenger Lucy Vose said she left her house at 6.30am and was still nowhere near work after 9am.
Another SWT customer, Daniel Green said his normal 48-minute journey to Waterloo had taken two hours 34 minutes.
One passenger, called Helena, who had to stand in the toilet on a train, tweeted: "I'm now crushed on to a train - standing in the toilets with other commuters. Fantastic."
Earlier she had written: " Absolute chaos at Woking, where my train from Worplesdon has just been dumped. "
Caroline Harrison wrote: "H ow can you subject people to this? Yet more signal failures, people rammed in like cattle. Sort it out!"
Katie Harrison tweeted: "I f you like surprises, travel with SWT this morning. You'll probably be able to get a train but who knows where it'll end up?"
Natalie Taylor wrote: " I could walk to London faster than SWT are going to get me there today."
Today's problems followed a power failure yesterday which affected services run by the Southern train company.
Last week a major power failure near Clapham Junction in south London led to some Southern passengers being stuck on trains for more than five hours.
South West Trains (SWT) said: "A fault with a set of points at an important junction between Esher and Surbiton is affecting all trains travelling towards London Waterloo.
" Our engineers have been able to make repairs to allow train services to resume, but please expect some recurrent delays. We have also experienced problems at Waterloo this morning with signalling equipment, which means we have had to continue to divert and alter services."
The spokesman said some alterations and cancellations might occur for the rest of this morning.
A South West Trains-Network Rail Alliance spokesman said: "Signalling problems at Waterloo and Surbiton have caused significant disruption to our services this morning. This has had a major impact on our passengers and we are very sorry for the inconvenience caused.
"The problem at Surbiton meant all trains towards London had to travel slower than usual, while platforms 8-14 were not available at Waterloo.
"Both issues have now been resolved and we are working hard to recover our normal train services as quickly as possible."
Mick Cash, general secretary of the RMT transport union, said: " The so-called Deep Alliance pilot scheme between SWT and Network Rail was supposed to be a model for the future but has turned out to be a total and unmitigated failure which has unleashed misery for passengers on a routine basis.
"The daily chaos on rail and Tube has reached unprecedented levels as thousands of extra passengers are thrown at an under-resourced, under-capacity system where cuts and private profit are the order of the day."
Delays on SWT carried on beyond noon.
To add to travellers' difficulties, there were long delays on Abellio Greater Anglia services between Shenfield in Essex and Liverpool Street station in London after a person was hit by a train near Harold Wood in Essex.
Hold-ups were as long as 60 minutes, with disruption expected to continue until 4pm.