@bloor How did the fraudster pass SCA?

probably depends somewhat on whether or not the bank believes you to have a prima facie legit claim, I think

Just tell them you wish to complain about their decisionmaking in relation to the fraudulent transaction and go from there

The 12 weeks thing is just down to the dispute-challenge-dispute-challenge-dispute-challenge back and forth of the chargeback process and response deadlines therein