As many as 100 people were left waiting at Wollongong station when their train terminated three stops early.
The 4.46pm service from Sydney normally stops at Coniston, Unanderra and Dapto after Wollongong.
At Wollongong it divides into two trains of four, with one going to Dapto while the other heads to Thirroul to become an all-stations to Port Kembla service.
Dapto’s Romeo Cecchele was on the 4.46pm on Wednesday night, when it terminated – without warning, he said.
He was notified by a passenger on the platform leaning into the carriage to tell him to get out.
Mr Cecchele joined what he estimated to be around 100 people on the platform at Wollongong, and asked the station attendant why it was terminating.
“He said that there are a lack of trains on the network and the Sydney Trains needs this old Tangara to go back to Sydney,” Mr Cecchele said.
He claimed the commuters then had to wait 20 minutes for the next service.
A NSW TrainLink spokesman said the 4.46pm service did terminate early at Wollongong but it was due to the usual Oscar train being replaced by a Tangara – which cannot be divided at Wollongong.
So the eight-car train was sent north to Thirroul as there would have been a longer delay for customers on the Thirroul to Port Kembla train if it had been cancelled.
He said commuters were “unfortunately” delayed 18 minutes before they caught the next train.
“NSW TrainLink apologises to these customers for the delay in completing their journey,” he said.