An elderly disabled woman was dropped off by a bus driver on a dark country Devon road against her wishes.
Mrs Chance said she was "absolutely terrified" by her ordeal
Dorothy Chance, who is partially sighted, was left at a bus stop on the Exeter to Cullompton road, about a mile from her destination.
The 70-year-old was spotted by a passing police car which picked her up and drove her to her daughter's home.
Stagecoach has said there had been a misunderstanding and the complaint was being investigated.
Mrs Chance, from Northallerton in North Yorkshire, had been spending the Christmas holidays with her daughter, Julie Flynn.
After a shopping trip in Exeter, she got the 1640GMT Stagecoach service from the city to return to Beare.
Mrs Chance said when she asked the bus driver to warn her when she was approaching the stop near her daughter's house, he refused and said she would need to ring the bell.
The bus stop was about a mile from Mrs Chance's destination
When she realised where she was the bus had passed her stop and the driver continued to the next stop on the route about a mile away.
"I've never experienced anything like it in my life," Mrs Chance said. "I was just absolutely terrified."
Ms Flynn said she was disgusted by her mother's treatment.
"I'm concerned that Stagecoach could allow a vulnerable, disabled pensioner to be dropped off in the middle of nowhere.
"And I'm concerned if they could do that to my mum, they could do it to other people."
In a statement, Stagecoach said: "There has obviously been a misunderstanding through human error and we will investigate the complaint and resolve it once the facts have been established.
"The care and comfort of our passengers remains our top priority."