A sprawling monument to opulence in one of Melbourne’s most expensive suburbs has had its day in court.

A five-bedroom marble-imbued mansion on Toorak Road has just about everything that would fit, other than occupants. The former owners have defaulted on their mortgage earlier this year, the National Australia Bank claims up to $8.22 million was still outstanding. Reports say as of July 18 that figure has risen with interest to leave the mortgage-holders owing $9.84 million. A case was launched in the Supreme Court to try and recoup the funds after a sale of the home fell through, Justice James Elliot said in a judgement that the mortgage-holders had no way to provide the money.

In efforts to raise the near $10 million owed, the Thompsons (who initially took out the mortgage) leased the home at $8000 per week to the billionaire head of a packaging firm. The Thompsons alleged that the later renters had pledged to buy the house, and are now trying to legally enforce the agreement.

The complicated legal mess may threaten the value of the house, according to Justice Elliot: “clearly, the property is a prestige property and there is a significant risk of the value of the property decreasing if an injunction were granted until the trial and determination of the proceeding [including any possible appeals].”

“I accept that there must be a real risk that, if the sale to the alternate purchaser is not allowed to proceed in the near future, that prospective purchaser may not be either able or willing to acquire the property in the event that [Mrs] Thompson were unsuccessful at trial,” Justice Elliot said.

The judge allowed the previous injunction to lapse, so that the National bank can move ahead with a re-sale. The house has been listed online.