That simply is not my understanding of it. You went into a bank with someone who owed you money. They defrauded the bank. If the bank had given him cash instead of a bank draft, then the bank would have no recourse to you.
Can we be clear about the result of the legal action. Were the bank forced to honour the draft?
If you were party to the fraud, I could see why the bank might try to dishonour the draft. But that does not seem to be the case here, although the bank may have suspected you.
Brendan