A pickpocket took Jacopo de Simone’s mobile phone and used his banking apps to steal £22,500.
He said his bank investigated but found him liable for the losses so he is still fighting to get the money back.
He is just one victim of the growing threat of mobile phone fraud and banks need to do more to tackle it, according to charity the Fraud Advisory Panel.
UK Finance, which represents 300 banks, said the industry was constantly monitoring fraud threats.
Criminals are stealing mobiles not for the device but to try to access finance apps to steal thousands of pounds, the Fraud Advisory Panel said.
Mr de Simone fell victim to the crime while walking around London Bridge in May 2022 when his phone was pickpocketed.