An elderly Sydney woman says she feels "violated" after a fraudster stole $25,000 from her by tricking her daughter in an impersonation scam.

Maureen Deans, 86, was left with just $200 in her St George Bank pensioner account after the scammer struck last month.

"How could they be so cruel? I'm horrified that people would do this sort of thing," Maureen said.

"I was left with no money to pay my bills."

READ MORE: Phone call reveals clever tactics used by 'Westpac' scammer

The nightmare began for Deans and her daughter Joanne on July 29.

On that day, Joanne got a text message from Medicare saying she had been in close contact with someone who had COVID-19.

It asked her to click on a link to order a coronavirus test kit.

Services Australia has issued warnings about similar scam SMS messages, but at the time Joanne was not aware of them. 

"Someone at my work had just tested positive to the coronavirus. I could just kick myself now, but that's the reason I clicked on the link," she said.

Do you have a story? Contact reporter Emily McPherson at scam report Australian banks were in a unique position to help shut down scams. 

The consumer watchdog has called on banks to adopt similar methods to those already in place in the UK, where banks match an account number to the name of the intended recipient.

Scammer red flags:

• Unsolicited contact: They unexpectedly call, SMS or email you claiming to be from a reputable business

• They know personal information: They have often already fraudulently obtained personal details like your name, ending digits on your credit card or approximate location, which makes them appear legitimate

• They want you to action something: They will often instruct you to complete an action while on the phone to them – like updating your banking details, increasing your daily payment limit, downloading an app or sending money to a "new" account

• They use spoofing software: They may use software to send you a fake SMS that appears to be from the business they say they're calling you from while on the phone with you to convince you the call is genuine.

(Source: Westpac Group)