I can't comment about Mandira, but I have had dealings with BNI.
I found a few of their people poorly trained, asking very silly questions, but generally very good.
By "Silly questions", I mean really daft stuff such as asking if I was allowed to deposit cash in an account under my own name.
I didn't mind them asking for a KTP when depositing cash into my own account, but I can't see a lot of point in it.
BCA have never asked a stupid or pointless question.
Both sets of staff have always been polite.