Customers have named the First Capital Connect (FCC) rail service as the worst in the country.
Just four in ten users said they were satisfied with the firm in a Which? survey.
Southern didn’t fare much better, with just 48% of passengers satisfied, making it seventh worst out of the 19.
Southeastern, which runs services from Hastings and St Leonards, was third worst in the country with a 43% satisfaction rating.
Virgin Trains achieved the best rating with 67% of users satisfied with its services.
But rail bosses at FCC and Southern questioned the accuracy of the statistics, claiming that 80% of their customers were satisfied.
Which? interviewed 7,000 rail users across the country.
Passengers were quizzed on everything from price and cleanliness to space and improvements.
One FCC passenger surveyed said: “The price has increased and the trains get more crowded. I never see any improvements for the extra money I am paying.”
Chris Barnard, 28, lives in Brighton and commutes each day to London.
He said: “For the money I pay the service is diabolical.
“The journey home is the worst. I can be standing all the way, which after a long day at work is the last thing I need.”
FCC, which is run by First Group, made £110 million profit last year.
The company questioned the validity of the survey, saying just 461 of its 170,000 daily users were questioned.
A spokesman said: “Our investment in the service is paying off with improved satisfaction with punctuality and journey times, the attitudes and helpfulness of our staff, the security of our services and the overall station |environment.”
A Southern spokesman said: “Having analysed the latest Passenger Focus survey, we know where our passengers have told us we need to improve, and we are focusing our efforts in these areas.”
David Sidebottom, from Passenger Focus, said: “The two surveys measure different things. Ours is very consumer-focused, asking passengers about their last journey.
“The Which? report is more of a general opinion survey about rail travel. Both are equally valid, they are just doing different things.”
See the latest news headlines from The Argus:
- Sights set on majestic bird
- Zoe Ball and Norman Cook announce their separation
- Elderly man found dying on floor ten hours after missed care appointment
- Police never gave us a chance - nightclub owners
- Unanswered questions over £100m housing project made councillor's stomach churn