As I work for a Bank I have a vested interest but thought I would share my stance on this subject.
As already pointed out the OFT ruling is for credit cards only and doesn't apply to bank accounts. But it may be a case of watch this space as this is a subject which is often being looked at.
As it stands at the moment banks will look at each case on its own merits. There is of course the possibility that a bank will not want to waste time dealing with a complaint and have the option of writing charges off, but only to get rid of a complaint rather than for any genuine justification.
Charges are a necessary evil in that there has to be a deterent for customers not to spend money they don't have or to plan to have money to pay direct debits or cheques etc. Having said that the question is what charge is fair in this situation and this is up for debate. The problem is that banks provide free cheque books, free cards, free online banking and free ATM's etc and therefore the areas where they can charge are higher than they probably need to be.
As for the original query, the charge taken on the 13th September should have been prenotified by letter or on a statement to prevent such a problem happening.
One final thing is that if you are not happy with the answer received, just take it higher up until you get a sensible response.
Good luck.
Cheers mate, appreciate the feedback. The opperative phrase the was found against the credit card companies was the use of charges as a deterrent. this is why some (not all) banks are settling already.
TSB are offerring 1/2 at most AFAIK.