If you get nothing out of this you have some ways of making things difficult for him.

No one can do anything with his bank account details but you can sign him up to most charitys to make payments by direct debits.

They will only ask for address and sort code and account number, something like this.

https://www.committedgiving.uk.net/a...nor.aspx?id=dd

Just sign him up to loads of them will be proper agro for him getting them cancelled especially when you dont know where they are coming from.

You may not get your money back but atleast a charity will get some!!