It has distressed the family considerably.
"It's that utter sense of false hope. When we met her we thought all our stresses and worries were gone," Manson Collins told the Christchurch Star.
"We thought we'll get the transplant, and by next year Maddie will be fighting fit and able to get on with life," she said.
Maddie, 13, has kidney failure with potentially life-threatening complications. Her family has been involved in a high-profile fundraising campaign to get her a kidney transplant and follow-up treatment in the United States.
They visited the Baltimore hospital where the operation will take place last month and were told the cost had jumped from $350,000 to more than $700,000.
About $170,000 has so far been raised for the St Margaret's College Year 9 student.
The family was approached by the woman via Facebook early last month who asked to meet in person at their West Melton home to give them a cheque.
The woman spent an hour at their home but didn't have the cheque, saying she needed to organise it with the bank.
Since then the woman has made many more promises to pay, which haven't eventuated.
The latest was yesterday morning when the woman said on Facebook Messenger she had arranged the bank transfer on Monday, but could not check it as she said she was on holiday in Dunedin.
In the message she told Manson Collins: "A transfer did go out but not too sure where. "Sorry about this mucking around it would be stressful time for you all. Not just Maddie but the whole family."
The constant hope of the donation was cruel.
"That could mean my daughter's life," said Manson Collins.
She said the woman seemed genuine when she visited the house. She was aged in her 50s.
She was completely bewildered about why the woman would promise them money or what she was trying to achieve.
The family hope to get a kidney transplant at the John Hopkins Hospital in Baltimore, as there is more chance of a donated kidney, and the treatment offered there would make it more likely Maddie's body would accept it, even if it was not a perfect match. Maddie's father, Adam Collins, donated one of his kidneys in 2012, but her body rejected it.
This year Maddie was told the daily dialysis treatment she is on has put so much strain on her heart, she was at risk of a heart attack, which made the need for a kidney transplant more urgent.
Attempts by the Star to contact the woman, whom the newspaper has decided not to name, have been futile.
But a family member the newspaper tracked down said the woman had been known to have "told some whoppers" in the past. He was unaware of the $42 million inheritance.
- Christchurch Star
