Product: Bank account or service

I am administering my father 's estate who passed away in XXXX. At my mother 's request and her estate planning attorney ( my parents had been married over 50 years at the time of my father 's death ), I am gathering information about their estate at the time of death. On XXXX XXXX, 2016, I wrote the corporate office of US Bank in XXXX XXXX, XXXX, provided a copy of my father 's death certificate, my mother 's acceptance of trust as successor trustee of their marital trust, and her notice of power for myself to act as her agent. I requested the account statements for XXXX XXXX and XXXX 2016 in order to provide the documentation their attorney requested in order to prepare their Estate Tax Return. 
On XXXX XXXX, 2016, I heard back from XXXX at US Bank, XXXX, who told me that she had received our request and that she would be forwarding it to the local branch office. She said that I should hear back from the local office by the end of the week. 
Three weeks later, on XXXX XXXX, Assistant Manager XXXX XXXX from the branch office at XXXX XXXX XXXX, XXXX, CA XXXX, called me and explained that my mother was at her office for the third time. She told me that in order to get these duplicate statements, I would have to personally visit a US Bank branch office ( there are no US Bank offices in XXXX where I live ) to fill out paperwork. I explained to her that we were not changing the ownership information, we just needed duplicate account statements. She demanded a certified copy of my father 's death certificate which I provided to her the same day ( attached letter is erroneously dated XXXX XXXX, but was sent on XXXX XXXX ). 
On XXXX XXXX, I received some ( but not all ) account statements presumably from XXXX XXXX although there was no cover letter attached. On XXXX XXXX, I emailed XXXX XXXX, and explained that I needed two items : 1 ) title information for XXXX accounts for which she sent a transaction history instead of account statements so that our estate planning attorney can determine the ownership of these accounts and include in the Estate Tax Return, if necessary ; and 2 ) account statements for one of the accounts that I did not receive any information about. 
XXXX XXXX wrote back : " With all due respect I wo n't be able to provide any information about your father 's or mother 's accounts since you are not a signer on those. I have provided your mom the statements that she requested, however any inquiry about her or your dad 's accounts need to come from her directly. She is the only signer on these accounts. '' In a later email, she again repeated that I would need to visit a local branch in order to change the ownership. I repeated that I had provided her with the power of attorney drafted by my mother 's estate planning attorney, executed by my mother and notarized, and that we only wanted account statements, not to change the title or ownership of the accounts. If there was information that US Bank needed from my mother, she was in the branch office on three separate occasions after I sent my letter on XXXX XXXX, and should have requested that information then. 
It has now been six weeks since I sent my request for information. The Estate Tax Return is due in another three weeks and US Bank is refusing to cooperate. Please help.