Passengers on a train traveling to Cardiff were told that they could get off at a station to use the toilets only for the service to go without them.
The train drove from Haverfordwest to Cardiff and the passengers were told they could get off at Carmarthen because the toilets were not working.
But they were shocked when the train left and left six of them on the platform.
A 15-year-old girl who went on a day trip with friends was said to have been one of the abandoned people.
The Sun reports that a stranded passenger said, "We heard that a pipe was blown and the train pulled out of the station."
It is understood that all the girl's friends were on the train with their luggage. The stranded girl's friends waited at the next station in Ferryside.
"We managed to find an official who said he was not informed of the train waiting."
It is assumed that the passengers were at 7:20 last Sunday.
The train was reported to have been detained in Swansea because Arriva Trains' stranded passengers had told Wales what had happened.
The passenger said, "I came to Cardiff, but the day was ruined.
"The affair was shameful and thoroughly confused, and in retrospect it was a farce."
Arriva Trains Wales has apologized for the incident and confirms to WalesOnline that it has made inquiries.
A spokeswoman for the company said, "We regret the inconvenience and inconvenience caused by this problem.
"We are conducting a comprehensive investigation into the circumstances of the event and our Customer Relations team has spoken directly with the passengers."
Arriva Trains Wales was also criticized this week after it was revealed that the company found 10% of the money in a wallet or wallet found on its vehicles.
The controversial policy was brought to light after a passenger was apparently told that he would return his wallet only for a fee of £ 2 plus 10% of the cash.
The railway company has since reversed its policy.