“Person who opened an account using a fake name now struggling to withdraw cash using his real name”I think it is both inappropriate and incorrect to describe what the OP's father did as ‘fraud’ or that he acted ‘fraudulently’. He opened the account with a different name than the one on his birth cert. But based on what we are told he did not act with deception to obtain an unlawful gain, or wasn’t money-laundering. So it does not appear to be a fraudulent act.
Opening accounts in names other than that on your birth cert was a fairly common practice in the past, for example many with first names of Immaculata or Concepta etc. preferred to use their second name of Mary or Joan, etc. in official documentation. It is unfortunate your father used a totally different name but as has been suggested elsewhere you really need to look at the terms and conditions at the time the account was opened.
I don’t see how the bank can walk away from this. They allowed your father to open and operate the account. It’s your father’s money. He doesn't appear to have acted fraudulently. It is for the bank to tell you what you must do to obtain the money, not for you to suggest solutions.. You could also look at the Central Bank’s Consumer Protection Code 2012. Consumer Protection Code 2012 - published 2015 (centralbank.ie), to see / ensure their response to you in handling your complaint is compliant with the code. [I recently has to deal with an institution on behalf of an elderly relative. We kept hammering them on ‘you tell us what we must do’. They did and the issue was sorted out.]
I’m no fan of the banks, but honest to God, at what point do customers and/or their families admit personal responsibility?
Why was nothing done in the interim?