Santander has issued a warning to bank customers as it called for more industry-wide action to help tackle unscrupulous scammers.
The lender said there should be a set of rules for all banks to prevent people being tricked into transferring cash to fraudsters.
There is currently a voluntary code to help APP scam victims - but banks don't have to sign up to this, leaving some victims out of pocket.
Some have instead introduced their own fraud rules.
APP fraud, or authorised push payment fraud, is where a victim unwittingly sends money to a scammer who is pretending to be someone they know.
In one heart-breaking case highlighted in a new report by Santander, a 61-year-old woman was tricked out of over £80,000.
The victim had been persuaded to make several payments to someone she had been playing an online game with - and the scam was only uncovered once she hit financial difficulty.
The scammer told her to lie about the reasons for the payments to avoid being caught. The woman has since been refunded by Santander.
Under recent proposals from the Payment Systems Regulator, all banks would be forced to reimburse anyone who loses more than £100.
They would be able to apply a lower threshold if they wish – except for cases where customers are involved in the APP fraud themselves or have acted with gross negligence.
PSPs would also be able to charge an excess of up to £35 for processing reimbursement claims. They would face a 13-month backstop deadline for resolving claims, starting from the date of payment.
In its new report, Santander said more than 70% of purchase scams start on social media.
The bank is now calling for more consistent data sharing and the mandatory use of confirmation of payee to help protect customers.
The bank also wants the Online Safety Bill to be brought forward and suggested higher-value or higher-risk payments should be subject to additional checks.
Enrique Alvarez, head of everyday banking at Santander UK, said: "The sheer scale and value of APP fraud can detract from the real impact of these crimes on individual consumers, who can lose more than just money - their confidence and mental health can also be significantly harmed.
"Unfortunately, we see this far too often, and it is time for us all to act together. The criminals who perpetrate these scams shouldn't be getting away with it."
A statement from the Payment Systems Regulator said: "We want people to be better protected if they are targeted by a scammer and have already set out proposals designed to give much greater and consistent levels of protection for victims of APP scams.
"Financial firms have to act to prevent fraud, and these proposals will also provide strong incentives on banks to do more to detect and prevent APP fraud in the first place.
"As soon as current legislation is updated, we will implement our rules as quickly as possible.
"In October, we also directed an additional 400 financial firms to implement the name-checking service, confirmation of payee. This will see more widespread adoption of the protections available to people making payments."
What to do if you've been scammed
You should always report a scam to your bank straight away - the sooner you do this, the better change they have of tracing down your money.
If you think any online passwords have been compromised, change these straight away.
You can report a scam to Action Fraud online or by phone on 0300 123 2040.
If you got a scam email, f orward it to report@phishing.gov.uk. It will go to the National Cyber Security Centre.
You should report an online scam advert to the Advertising Standards Authority (ASA).
If the scam involves cryptocurrency, investments, insurance or pensions, report it to the Financial Conduct Authority.
