She was sentenced to 16 years and seven months in prison, but last month appealed against the sexual violation conviction and the sentence.
Her case was heard in the Court of Appeal in Wellington, where her lawyer, Chris Tennet, said the jury returned inconsistent verdicts on the sexual violation charge.
Torrance was found guilty while her co-accused was found not guilty on the charge.
Tennet also argued more of a discount should have been allowed in sentencing to factor in Torrance's mental health issues, and her grief and PTSD following the suicide of her daughter.
Her anger towards the victim was fuelled by the belief the victim had stolen some items belonging to Torrance's dead daughter.
In a decision released today, the court dismissed Torrance's appeal against the conviction, but granted the appeal against sentence.
She was instead given a sentence of 14 years and 11 months, with a minimum non parole period of seven years and six months.
While the court found the sentencing judge's starting point was "unimpeachable", it said the expert evidence showed she was "suffering from intense grief, severe depression, high anxiety and post-traumatic stress disorder" at the time of the offending.
"Ms Torrance isolated herself from others and was spending long periods at her daughter's grave site, both during the day and at night. Ms Torrance believes that during one her nightly vigils at the cemetery, [the victim] stole some of her late daughter's possessions, including jewellery of high emotional value," the decision said.
Some of this expert evidence had been requested by the sentencing judge, but was not available at the time of sentencing. The Court of Appeal ruled it could now be taken into account.
It ruled there was a link between Torrance's poor mental health at the time, and the offending.
"Of course, this could not in any way justify the extent and level of cruelty involved in
her offending, but we are satisfied it was nevertheless a contributing factor that should
have been recognised to a modest degree in assessing Ms Torrance's overall level of
culpability."
The court ruled a further 10 per cent discount should be allowed on the sentence to make up for this.
The attack
During the trial, the court heard the attacks started after Jones became angry with the young woman because she believed the woman had slept with her partner.
Then in April 2016, the young woman was lured to a former friend's Newmarket flat under the false pretence of a drug deal.
There Jones and Torrance ambushed, bashed and tasered the woman before threatening to repeat the attack if she did not leave Auckland for good.
One month later, Jones and Torrance, along with two others already sentenced to prison terms - Michelle Blom and Jaclyn Keates - kidnapped the woman from near Karangahape Rd and took her to Blom's west Auckland home.
There she was bashed with a cricket wicket and bat and sexually violated.
After being held captive for about 22 hours, Jones, Torrance and Blackett drove to Conical Peak Rd with the young woman tied, wrapped in a tarp and thrown into the back of a Hilux ute.
After trying to strangle the woman, Blackett took a hammer and delivered at least 10 blows to the woman's head, causing multiple fractures and depressing her brain by 2cm, prosecutors said.
