A woman's seven-year obsession with her former boyfriend made him feel like he was only safe when she was in prison, a court has recounted.



The man has moved on to another relationship and he and his partner have spent about $38,000 including on lawyer's fees, repairing property damage and installing home security systems.



The woman, Kerryn Mitchell, 45, has today lost an appeal against a sentence of two years and one month's jail imposed in Wellington District Court in September.



On the morning her trial was to have begun she pleaded guilty to charges of intentional damage and breaching a domestic protection order.



The following month Mitchell was back in court on civil cases relating to her time in custody.



While in prison earlier this year Mitchell had destroyed four mattresses she said were not fit for the purpose. A judge has struck out her civil claim alleging that leaving her without a mattress for six days had denied her the minimum entitlement for a prisoner.



But in future she can pursue a claim for damages over the purported reasons prison authorities withheld her copy of The Dominion Post and letters she had written to another prisoner.



In the Court of Appeal decision issued today the three judges said Mitchell had gone on a rampage with a tyre iron at a former boyfriend's house in December last year.



Mitchell left abusive messages on his phone blaming him for a protection order that had been in force against her for five years.



At about 11.30pm that night she went to his house with a tyre iron and smashed most of the windows she could reach, two outside lights, and broke a glass door pane to get into the house.



A friend of the victim told Mitchell that the victim was not home so she left, smashing the letter box with the tyre iron as she went.



"She proceeded to sit down, drop the tyre iron and waited for the police to arrive," the Court of Appeal judges said in their decision.



Mitchell was sentenced at Wellington District Court in September to the jail term. She was also ordered to pay $2863.41 reparation for the damage but today the judges said there was nothing to indicate that the reparation would be paid.



The Court of Appeal said Mitchell's relationship with the victim ended in about 2005 and in April 2008 a protection order was obtained against her.



The order, which was later extended to cover the victim's new partner, has been breached nine times.



The December window smashing was the latest evocation of Mitchell's "seven-year obsession with the victims" which was unusual and concerning, the court said.



"Ms Mitchell's conduct over the five and a half years in which the protection order has been in place has been extraordinary," it said.



In his statement for the District Court sentencing the victim had said he only feels physically safe when Mitchell was in custody. His partner keeps the doors locked all the time.



Mitchell's previous convictions include 38 for assault of various kinds, two for injuring with intent to injure, and nine of wilful damage, as well as threatening to kill.



"Even excluding her offending against these victims, it is a record of violence and defiance of authority," the Court of Appeal said.



The court said her "most unfortunate personal circumstances" had been recognised many times by sentencing judges but she continued to offend.