Who I have the same questioned this topic

I have Power of Attorney for my ailing father's account.  I've sent it to Verizon and they have acknowledged receipt saying that they will abide by the terms of the document.  However, every single Verizon representative has refused to grant access to me to his accounts.  I have tried chats, and several phone calls, and have even gone into a Verizon store.  I drove to my father in the hospital and used his phone to get through security which was supposed to provide me a temporary password.  That did not work either.  What exactly do I have to do to become a manager on my father's account?