Really bad service, when trying to access funds to close the account

I have an investment account, it was on my sons name, he turned 18 dec 2024, suddenly 2weeks ago, the investment disappears from my profile, no notice from the bank or nothing, i phoned the bank, they say, he has to go to the bank to sort it out, i explained, he does not live here, they did not care, so he came home to go to the bank, when we were there, the lady was rude and rather unhelpful, however, she said, he must open a profile, so we did that, he gave his id, did the finger prints etc, but was not able to manage the investment account, they tried phoning the investment number, with no joy, we then left, as the service was pathetic. Now when my son wants to go into the profile we made him, it says that it needs legal documents, of which we gave the bank, he is not able to do anything, and he cannot phone the bank, as he is working, so now we are stuck again, this is rather untasteful, and we are disgusted with the service. How can he get the legal documents sorted? we are going to close all our accounts with FNB, as this is getting on my last nerve, as when you ask nicely, u get treated like dirt.