In the Chinese community, it is common for people to change money privately among friends, family and acquaintances.
The woman claimed she brought $100,000 in cash and the customer agreed to transfer the equivalent Yuan and wait at the store until the transfer showed up in their account.
But the man left the store while she was cooking and her husband was busy in the store, she said.
"My husband send me a WeChat message asking whether the money has turned up. I said it hasn't. He said 'while I was busy working, he has already left'."
She said she trusted the customer, who had been visiting her dairy for four or five years.
She also said she messaged the customer on WeChat, he asked her to wait, and eventually she received ¥14,000.
"Then I can't get in touch with him anymore. At first when I tried to call him, there was no pickup, but on the second day, his phone was turned off - I can't reach him at all," she said.
"I even sent him a photo of my mother-in-law. I said 'look, this is what my mother-in-law looks like, can you please return the money to me. The money was meant to be used for her medical treatment and to save her life but you took it away. I was trying to persuade him, but he never replied."
Police said they were investigating an allegation of fraud and two other separate cases - one is a civil matter and the third involved a report of a scam in May.
In relation to the scam investigation, police have charged a 31-year-old man with obtaining by deception.
He is due to appear in the Auckland District Court later this month.