Bank Account being held hostage

My parent has relocated overseas several years ago. She changed her email address via the online portal which was accepted, unfortunately, subsequent attempts to login request an authentication code with the code being sent to an email address she held over a decade ago.

Multiple attempts to contact the bank have been made to correct this very simple to fix issue but with no success. Call centre staff advising that they can't do anything to help and that my parent should contact the specific local branch they used to be linked too - this seems bizarre that a simple communications details update cannot be done following some security questions. This advise even went as far as suggesting that they physically visit their old local branch - all this just to update a simple email address.

Eventually they were guided on to speak to the international banking team, who seemed potentially helpful, although they requested email scans of bank cards which seems very odd and not good practice at all. To date they have still not updated any details or attempted to get in contact, despite this matter dragging on for months.