Danske Bank have not closed. They are still registered as a credit institution with the Central Bank of Ireland and have offices in Dublin.
They are in the process of closing their non-corporate banking here but have not completed this. They previously out-sourced the administration of accounts to Pepper but brought this back in-house last year.
I would suggest contacting them at their Dublin office through the contact details on danskebank.ie. If you're not happy with their response consider their complaints procedure.