Teenager dragged into a car by her hair, cut and bashed by her mother and grandmother to "teach her a lesson".

“How could you put me through this? How could you attack your little girl?”

It was the question a tearful teenage girl asked her mother.

Her mother accused of orchestrating a sustained attack on the 15-year-old because she thought the young girl had stolen something from her and she decided to “teach her a lesson.”

To drag her into a car, beat her and cut off her hair.

A crime committed by her own mother who has now been found guilty of the crime.

The mother dragged her daughter into the car and bashed her. Via IStock.

A court in Adelaide has heard that the 15-year-old girl was dragged into a car by her hair by her mother and assaulted while she was in the backseat while her grandmother drove the car.

The ABC reports that the two women were found guilty yesterday of aggravated causing harm with intent against the girl.

The court heard the victim's mother was the main offender and her grandmother was found guilty on a joint liability basis.

Prosecutor Jemma Holt told the court that in 2014 the victim's mother enlisted the help of her own mother and the victim's former partner to carry out the "premeditated attack" at Aldinga Beach, in Adelaide's south.

"On the prosecution's case, it was her plan to confront, intimidate and scare her [the girl] to teach her a lesson, that is because she thought [the girl] had taken things from her home and she had got away with it," Ms Holt said.

"[The grandmother] was driving the car ... it was [the mother] who confronted [the girl] dragged her into the car, on the prosecution's case by her hair and then subjected her to a sustained physical attack in the vehicle.

"This includes blows to [her] face and upper body."

The girl's hair was cut off with scissors by her mother and her ankle was broken in the attack. The ABC reports that the 15-year-old was bitten her on the nose by her mother and sustained cuts to her face and ears from a pair of scissors.

The teenager told the court this week that she grew up in a neglected and violent home because her mother took drugs and that she now suffers from panic attacks.

“I didn't go out for a long time because I had nearly no hair ... I didn't know how to tell people my mum had cut my hair and bashed me,” she said.

“If two women who are meant to love me can do that, then how can I trust anyone?”

"How could you put me through this? How could you attack your little girl?"

 "I didn't know how to tell people my mum had cut my hair and bashed me,” she said. Via IStock.

The court heard that the girls' grandmother had been struggled with a psychiatric condition since the loss of her son, who was murdered overseas and that this type of behaviour was "out of character" for the 58-year-old.

"This offending is so against the grain, it is very difficult to explain why it happened," defence lawyer Todd Grant said.

"I ask your honour to take into account the significant psychological conditions that she must have been suffering at the time," he said.

"It is clear that she had been a lady who throughout her life who has been devoted to her family."

The girl's mother was already subject to a suspended sentence bond for previous drug-related charges.

The mother and grandmother will be sentenced when the court reconvenes for further sentencing submissions in July.