There's calls for South Western Railway to have its franchise removed by Lib Dem leader Sir Vince Cable.
He's told the Commons only a third of passengers feel they're getting value for money.
He said: "I'm sure this is deteriorating by the day.
"The company underbid for subsidies and is now financially stretched, it appears to be struggling to maintain payments to its financiers and the consequence is that passenger welfare is being sacrificed and the investment that was promised is not materialising.
"I think there are some serious questions for the Department and Minister about how this franchise was allowed to take place resulting in a serious deterioration of standards.
"In relation to the franchise, there are essentially two options –-one of which is to take the franchise away and replace the existing company with another, preferably a public service company but there are a variety of options.
"The other is to impose on the franchise a set of performance-related measures, so the company is only paid when it actually delivers on its undertakings."
A South Western Railway spokesperson responded by saying: "We recognise that we haven't delivered the standard of performance expected for our customers.
"That's why earlier this year we took action to commission an independent review of performance on the network.
"Following the completion of that review, chaired by Sir Michael Holden, we now have a blueprint to help us improve performance - and the good news is that many of the recommendations in the report had already been identified and are underway.
"Typically, around 25% of delays are within SWR’s control with the majority related to train reliability issues and that’s why we are making a £5m investment in making our trains more reliable.
"Around 70% of delays are related to infrastructure issues and Network Rail is investing £2 billion over the next five years to run the railway and help give passengers more reliable journeys.
“We’re investing £1.2bn over the course of the franchise which will go towards improvements including improved performance, better station facilities, more seats, innovative ticket buying options and better customer information.
"£895m of this investment will bring a brand-new fleet of 90 trains comprising 750 air conditioned carriages with toilets for use on suburban services, and £110m on train refurbishments.”