I don't know if this is the requested 'positive' comment, but I have just been through this myself, my main problem being that I bank on line and you cannot print off statements which include your name and account number.
I was equally outraged by the intrusion into my privacy but if you want and need the benefit you will need to compromise. I obtained hardcopy statements from my bank and handed them over.
I also made many references to involving a local councillor when they still seemed to be dragging their feet processing the claim. This seemed to bring about a prompt result
The purpose of it is to prevent fraud.