If you’re paying over the odds to strangers online ALWAYS do it through a site allowing you to pay by credit card.
It all goes pear shaped and you can instigate a charge back. NEVER do a bank transfer.
As for the OP, it might seem a pain but report it to the police and your bank. The bank account number and sort code are easily traceable. It’s fraud and should be chased by the cops (don’t hold your breath though). Certainly if it’s UK bank account it’s a 5 minute job for them to find out who the scumbag is.