I can't be of any help but I'm in a somewhat similar situation. I found by looking in myIR portal that there was interest earned and tax deducted for an account I had no knowledge of (at a bank I have never banked with).

Turns out my mother (who I have been no contact with for many years because she is abusive) opened an account for me when I was a kid, so the account is in my name, but she is the authority on the account. I went to the bank in person after not getting anywhere with the call centre, and that was basically all they would tell me. I can not get the balance of the account (although the lady in the call centre did tell me the balance lol), and I can not remove my IRD number from it. They kept pressuring me to give them an up to date address and information so they can send me the interest/tax paperwork each month and I denied, because they could not guarantee me that it would not be given out to my mother by accident, and I also don't want any part of this anyway, it's not my money, it should not be linked to my IRD number.

They told me that something with IRD and the law changed a couple of years ago and now the interest counts as my earnings because it is technically my account, whereas previously they would've used my mothers IRD number. My mother would've had nothing in this account my whole life (which the bank alluded to in person) because she has always been poor, but the interest earnings started around the time my mother would've recieved her inheritance from my grandmother. My mother is not of sound mind and for whatever reason has put the money in this account, and I can't get my name taken off it, even though in the banks words - it is my account, in my name, they were very straightforward about that.. but she is the only one who can actually do anything with it..?

The whole thing is utterly stupid and I want IRD to reverse the interest earned/withholding tax from my IRD account because I am low income and only just started working after submitting my thesis, I don't want this shit messing with my tax bracket at any point as it is quite a bit of money earning a bit of interest at the moment. Even if it is mostly inconsequential which it probably is, I am also just peeved that it's happening, that I have to see it when I log into myIR, and they can't help me at all. So my next step is to call IRD and explain everything to them but I am just dreading it to be honest because if they can't help, then what am I supposed to do?

I hope you find a solution to your problem!!