While they had no regrets at stopping to help, the family were devastated to return to Verdouw's daughter's car and discover it had been broken into.
The break-in occurred on a street near Silo Park between 12.30pm and 1.45pm, he said.
Several thousand dollars worth of belongings vanished.
"The items stolen had a monetary and sentimental value. NZ-based daughter lost a borrowed overnight bag, filled with shoes, clothing and an expensive set of cosmetics. The son lost a small day pack, which included his passport, phone, books, but also his diary of the past five years.
"Our [younger] daughter had her work laptop and hard drive stolen."
Verdouw's younger daughter had copped a stern response from her employer, who asked her to pay a AU$1000 ($1053) downpayment for the laptop until insurance could be sorted, he said.
"She was just beside herself when we found out. Her first thought was 'I'm going to lose my job'."
The family did not have travel insurance, but are checking to find out if they are covered through their credit card provider.
The break-in was reported to Auckland police, he said.
A police spokeswoman said they were investigating.
"While no items have yet been recovered we are following a positive line of enquiry."
The experience soured the end of their four-day visit, but had not put them off Auckland, which they had visited several times and held great affection for.
They also had no regrets about stopping to help the unwell woman, even though the break-in may have occurred while they were with her, Verdouw said.
"It's just one of those things you do."