I've been reading all the success stories from this website

and actually got round to sending my first letter with the cheque requesting all my statements so I can get this whole matter underway. Can anyone tell me how this information normally arrives - I'm imagining a box of copy statements - probably huge !! - exactly how far back do the banks normally go at this first request stage ?
I'm absolutely terrified, but determined to keep going - my account was always fine until the charges started -I'm quite sure there's someone at the bank pressing a button every time they see my name and going - ha, another charge to you !!!.
Any words of wisdom very gratefully received.