I once had 'a bliddy bank clerk' do something she didn't have authority to do on my bank account.
Situation: Divorce and maintenance argument. Ex puts sum of money in my account. Ex decides he wants it back. Ex persuades bank clerk it was a mistake. Bank clerk removes money from my account!! I demand it back. Ex refuses. Bank sides with ex initially. (Ex is a longstanding business customer with more clout than me.)
Eventually problem went to area manager. Because bank clerk had no authority to remove funds from my account, I was re-imbursed (with many apologies and extra amount for the distress caused)... from the bank, not the ex.
So...surely the bank could be in big trouble if the clerk had no legal authority to act as he/she did. Especially as it is resulting in loss of funds belonging to a vulnerable adult.
Start complaining!!! I think you should demand that the funds be replaced. That they should not have been removed without your permission. Lay it on thick explaining the dire consequences of their (illegal) actions.
Go for it! Demand they refund the money lost! You have nothing to lose and it is soooooooo satisfying to take on the bank and win!!