Sefcu review: Fraudulent closing of an account

On 8/1 my mother passed. On 9/21 i was granted to be admin of the estate by the Rensselaer County surrogates court. On 9/24 I spoke with the Manager of the Clifton Park branch. Joe Scriver regarding my mother's accounts (my boyfriend was with me as he had to make a truck payment at the same location so i have proof we were there). He informed me that the accounts were locked and that no one besides me as the admin could close them. I even have his handwriting on the printouts he gave me when i questioned some of the withdrawals. When asked if he wanted to make copies of the estate paperwork for notation i was informed that wasn't necessary as I was not closing the accounts that day and was assured again that the accounts were fine. (I only went in to get a history on the account to match up my mother's final bills). On 10/4 I went to another branch closer to home to officially close the accounts to transfer the funds into the bank i had set up and was informed that the accounts were closed by my younger sister on 9/28. She filed a form with them stating she was the only survivor known (she fraudulently claims she didn't know my last name or address yet claims she lives at the same address) and that there was no estate set up. When there in fact was an estate and Sefcu was notified when i spoke with the General Manager. Sefcu has given me the run around. I have even been told that their loss mitigation department is not client facing so I cannot email or call them. (I was told this by the General Manager Joe Scriver when i called him to ask how this could have happened as he had given me his personal cell number if i had any issues) If the General manager had made notation or took copies of the estate paperwork to put on my mother's file or some notation. Or if the branch my sister did this at had done due diligence and checked with the surrogate court to see if an estate was established. This would not have happened. The accounts were closed out in excess of 10k. I feel the Sefcu manager failed to protect my mother's accounts.