One in five passengers is "resigned to poor service" on Britain's railways, according to a new study.
Long-term issues have resulted in "high levels of disillusionment", a report by dispute resolution organisation Ombudsman Services found.
Complaints about rail services increased by almost a third (31%) to two million last year, its survey of 2,477 people suggested.
The most common complaints were over punctuality, poor customer service and overcrowding.
Public transport campaigners said it was "simply unacceptable" that some passengers were paying "thousands of pounds for poor service".
The survey reflects recent figures published by regulator the Office of Rail and Road (ORR) showing that the rate of passenger complaints per 100,000 journeys between July and September last year was 13% higher than the same period in 2015.
The ORR noted that methodology changes might have affected the data.
Campaign for Better Transport campaigner Lianna Etkind said late or overcrowded trains can "genuinely blight people's lives" and claimed no other service industry would "get away with treating its customers so appallingly".
She went on: "Regulators need to ensure that when people complain about their train service, they aren't just fobbed off with a copy and paste response but that real action is taken."
Rail passengers with a complaint must contact the relevant train operator in the first instance, before going to Transport Focus or London TravelWatch if they are not happy with the response.
In December, Conservative MP Tim Loughton introduced a Bill to Parliament calling for a law change to establish a rail ombudsman, which would oversee a simplified scheme aimed at hitting train operators harder financially to act as an incentive to improve services.
The Department for Transport (DfT) said more than £40 billion was being invested to improve Britain's railways.
A spokesman added: "The Department for Transport monitors the performance of all train companies against a number of areas, including delays, cancellations and short formation of trains.
"There are penalties for those who do not meet the desired standards."
The Rail Delivery Group (RDG), representing train operators and Network Rail, accepted that on some parts of the network passengers are not getting the service they expect.
It noted that punctuality has been hit in London and the South East owing to congestion, industrial disputes and major upgrade work.
An RDG spokesman added: "The long-term trend is one of falling complaints from rail passengers but we know we must do better which is why we're delivering a raft of improvements."
Customers made an estimated 55 million complaints to all businesses last year - up 6% from 2015, the Ombudsman Services study found.
The most commonly complained-about sector was retail at 24%, followed by telecoms (13%), energy (10%) and transport (7%).
Some 17% of people say they have complained about problems before but nothing has changed.
Chief ombudsman Lewis Shand Smith said: "Consumers feel that complaining is often a waste of their time, because they see no change in the behaviour of big business."