Wow, that is almost criminal.
If you are willing to share, please send me a personal message as we are trying to demonstrate to UKBA that their IEB often gives out misleading and totally incorrect information.
The case worker that reviews your case will use the following document to make a decision:
http://www.bia.homeoffice.gov.uk/sitecontent/applicationforms/pbs/tier1generalguidance.pdf. There is nothing more or less to it. It is the full summation of Tier 1 General. Follow what it says over and above anyone else. If you have a hard time understanding it, that is a different story, but generally it is very precise and clear.
As far as the maintenance funds, EVERYONE has to supply 3 months were of proof of maintenance funds. There is nothing I can find in there that says anything about 12 months, etc. It says the following about those making the application in country under paragraph 196:
Applicants in the United Kingdom seeking further leave to remain must have at least £800 of personal savings which must have been held for at least three months prior to the date of application.
I am not sure what the IEB person was on about. The only only thing is that there was a recent change that said the proof of maintanence had to be within 7 days of the date of the application being submitted but now is 1 months.
As far as the closing balances each month (which is strange if you only have to give one month according to them) is not mentioned in the guidence as you point out if you are submitting paragraph 203(ii) proof of maintenance (which it sounds like by what you say).
Follow the Guidence. If you follow the Guidance and they refuse you, you will have grounds to have the decision overturned on an adminsitrative review, if you follow the advice by the IEB, you have absolutely no recourse (which is another thing we are attempting to deal with as well). Even if you had professional assistance by a OISC registered advisor you could take some action if they gave you bad advice and they don't even work for the Government.