Mrs Serepisos fought the issue with an argument that the mortgage lender "sabotaged" the sale, including by selling it well under the appraised value of $995,000, taking 18 months to sell it, and ignoring a higher offer.
In the decision, High Court Justice Rebecca Ellis noted Mrs Serepisos made no repayments to the mortgage, nor any Wellington City Council rates, or Body Corporate levies.
Ellis said the circumstances of the debt were "not favourable" to Mrs Serepisos.
"The reality is that she borrowed nearly half a million dollars and made not one repayment under the loan.
"There is no suggestion that she attempted to meet her commitments at an early stage but then fell into arrears, only to become overwhelmed by the rapid accrual of default interest."
Ellis noted that Mrs Serepisos did not give evidence to the court, but that her son Terry Serepisos did on her behalf.
"Mr Serepisos' evidence commenced with the unsual statement that he had a power of attorney for his mother, and was authorised to give evidence on her behalf.
"No objection was taken to this, no doubt on the grounds that Mrs Serepisos herself is elderly and reportedly has poor English.
"It seems tolerably clear that Terry Serepisos was, in any event, her guiding hand in relation to the transaction at issue."
Mr Serepisos had been a tenant in the apartment, but when it came up for sale General Finance removed his personal affects and had the locks changed.
Mr Serepisos told the court the extra money wouldn't still need to be paid if General Finance had sold the apartment to the buyer he had lined up.
In May 2016 Mr Serepisos had met with a man called Mr Chin, who had expressed an interest in buying the property. But Mr Serepisos no longer had access to the apartment, and was unable to get the keys through the sellers.
Mr Chin signed an affadavit to the court that he would have been willing to pay up to $800,000 for the apartment.
But Justice Ellis said it seemed to be a case of too little, too late, as a lower sale price had already been agreed.
"Put simply, if Mr Chin's interest in the property did not materialise until after that May 3 [settlement] date, there was nothing GFL [General Finance] could have done about it," she wrote in the judgement.
"As noted earlier, it has not been seriously suggested that GFL could, in the circumstances, reasonably have been expected to refuse an unconditional offer, for a price consistent with all other known interest in the property, on the chance that a better offer might happen to come along."
Justice Ellis dismissed Mrs Serepisos' counterclaims, and ordered her to pay $332,284.88, as well as costs.
Terry Serepisos was bankrupted in September 2011, when his portfolio of about 150 residential properties and commercial buildings was valued at $232.5 million, while his debts stood at $204m.
He was discharged from bankruptcy in October 2014.
Before his bankruptcy he was a high-profile celebrity, including his appearance on The Apprentice New Zealand, holding the licence to the Wellington Phoenix football team, and sponsorship of the 2009 Wellington Cup at Trentham racecourse.
