When Clare Wainwright checked her bank account on Thursday, she did not expect to find herself $24.5 million richer and her mortgage paid off.

Ms Wainwright said she felt "quite great actually" when she saw $25.1 million had been transferred to her account at the National Australia Bank.

"I'm a lawyer, which is why I haven't spent the money," she said. "Mostly because I figured it wouldn't play out that well trying to play dumb on that."

Yet Ms Wainwright's efforts to alert the NAB to the mistake appear to have been ignored.