Damn, the title sounds like some BSDM movie!
One thing that struck me:
It wasn't up to 10 minutes after he contacted his bank I received the payment in my account.
I don't believe that the bank was someone able to solve and transfer your money the balance reflect in your account in 10 minutes after not being able to do in 2 days, you said he had proven that he had sent the payment with documents, by chance can you compare the proofs with the current transfer as I tend to believe that as in many cases he didn't pay at all the first time and only under pressure and maybe because of a good fluctuation in exchange rates he agreed to do so!
I can't really tell if he never did or did the transaction the first time. But from the alert I received I can see two different dates 14/09/2023 which is the first day of the transaction, and the second date 15/09/2023 was the day I received the payment.