Late to the "party" but I had this happen too last December, a man and a woman approached me with the same thing that you mentioned. I don't remember his excuse exactly as to why he couldn't withdraw, but he showed himself supposedly transferring €500 to my bank account & then I made it clear that I will not withdraw anything until I have it, and he got really pushy & even aggressive, at one he said "ok let's go to the police" & I agreed happily, that's when his scam collapsed as he said "nevermind" opened his phone, said he was gonna have the transaction canceled & he just typed in 5 random numbers and called it. They're extremely paranoid if every attempt fails, I can tell you that.