The number of rail journeys made using season tickets has fallen to a seven-year low, as passenger groups warn that fare rises are forcing commuters to abandon the train.

Figures slipped out by the Department for Transport before Christmas reveal a 9.4% drop in season ticket sales between July and September 2017 compared with the same quarter the previous year. There was a double-digit drop the previous quarter.

The Office of Rail and Road quarterly figures note that the number of journeys between July and September 2017 made using season tickets fell to its “lowest since 2010-11 Q2, with 15 million fewer journeys made compared to this time last year”.

Some of the fall can be attributed to strike action. But as commuters prepare to return to work on Tuesday – when fares will rise by up to 3.6% – the Campaign for Better Transport said it was becoming evident that rail passengers have had enough.

“Rail commuters are fed up with being used as cash cows for government coffers,” said Stephen Joseph, chief executive of the Campaign for Better Transport. “This year’s rise is the highest for five years, at a time when wages aren’t increasing, and there’ll be real anger on the trains about this. But also there are signs that commuters are just voting with their feet and simply changing their work or homes to avoid the ever more expensive daily commute.”

Many season ticket prices will rise by the full 3.6%. A year’s travel between Cheltenham Spa and London will increase from £12,784 to £13,244, Peterborough to London from £7,592 to £7,864 and Leeds to Birmingham from £7,700 to £7,976. By contrast, the latest figures from the Office for National Statistics confirm that average weekly earnings fell by 0.2% in the autumn compared with the previous quarter, once inflation was factored in.

Labour said regulated fares – such as season tickets and standard returns, which comprise almost half of all fares – have now risen by 32% since 2010, more than twice the level at which median wages have increased in the same period.

Regulated rail fare increases are set by the government. Since 2014 these have been capped at the previous July’s retail price index, which, unlike the consumer price index, includes mortgage interest costs and council tax. As a result, RPI inflation has consistently outpaced CPI, something passenger rights groups say is unfair on UK rail users, who pay more for train travel than their European counterparts: figures buried in the latest annual report for the DfT reveal the department’s net income from passenger ticket sales totalled almost £1.3bn last year.

Aware of mounting anger over prices, the government pledged to run pilots exploring different pricing tariffs. They were supposed to start last May but the government admitted just before the festive break that none has yet commenced.

“Ministers keep promising fares reform but even pilot [schemes] have been delayed and users are seeing very little change on the ground,” Joseph said. “We need simpler, fairer and cheaper rail fares, a freeze on any further rises and flexible season tickets to help the growing army of part-time workers.”

Passenger groups are set to protest at stations across the country this Tuesday. Labour’s transport spokesman, Andy McDonald who will join Keir Starmer, the MP for Holborn and St Pancras, at a protest at King’s Cross, called the latest increases “staggering”.

“Passengers are at the end of their tether. It is more evidence that the rail system is too fragmented and complex and run for the profit of private enterprises, not in the [public’s] interest.”

A DfT spokesman said fare prices were kept under constant review and that 97p out of every £1 paid by rail passengers went back into the railways.

“We are investing in the biggest modernisation since Victorian times to improve services, providing faster and better, more comfortable trains with extra seats. This includes the first trains running though London on the Crossrail project, an entirely new Thameslink service and continuing work on the transformative Great North Rail project.”

A spokesman for the Rail Delivery Group, who represent train operators, said it disputed some of the claims by the campaign group.

“Total commuting and business trips on rail increased by 18.1% between 2010 and 2016 according to National Travel Survey data. The National Rail Passenger Survey also shows that less than half of commuters travel on season tickets which is because of more use of contactless and oyster card payments,” he said.