Unhelpful and unable to rectify sign up issue

My niece is trying desperately to open an account with Discovery Bank to deposit her inheritance but her cell phone number has a random passport number and ID number registered against it on the system. Numerous calls to the call center have come to naught as she gets told that someone will sort it out and call her back. I understand that it is lockdown but this has now been going on since July. How difficult is it to rectify an error Discovery Bank created before she even started trying to sign up?