Actor Toni Collette and her musician husband David Galafassi will receive just over $74,500 in change after handing over $700,000 in damages to a couple of aggrieved ex-homeowners.

But the famous duo have also been ordered to foot most of the latest bill in what has been a lengthy court battle, sparked when they reneged on a promise to buy a multimillion-dollar Paddington terrace three years ago.

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Collette and Galafassi had agreed to buy the eastern suburbs home of Industrie clothing founders Nick and Susan Kelly for $6.35 million in 2011.

But on December 30 that year, the day they were to complete the transaction, the couple backed out, saying they didn’t have the money.

In an email sent a month after the terrace purchase fell through, Collette and her husband pleaded with Ms Kelly not to take her family to court.

“It just makes a very sad situation much worse,” they wrote.

“We can no longer buy your beautiful house. Again, we apologise profusely. We don’t have the finances to go through with the purchase.

“For the sake of both our families, I implore that you find a way to settle this less publicly.”

The Kelly’s home eventually sold in 2012 for $5.5 million and they sued Collette and Galafassi for the loss as well as interest and land tax.

Collette and Galafassi were ordered in the NSW Supreme Court to pay the Kellys nearly $815,000, though this was reduced on appeal to just over $600,000.

But by then Collette and Galafassi had already shelled out $700,000 and on Thursday the NSW appeal court’s Chief Justice Thomas Bathurst and Justices Julie Ward and Fabian Gleeson ordered Susan Kelly to hand back the amount overpaid with interest.

They also ordered that Collette and Galafassi pay 90 per cent of Ms Kelly’s costs in the appeal, up from an earlier order that they pay 65 per cent of costs.