on a couple of occasions it was made quite clear to me that by paying extra charges, certain minor discrepancies in my paperwork could be rectified/overlooked and i would be granted the extension i was seeking without any further inconvenience.They want the "i"s doted and the "t"s crossed to protect themselves from future problems.
........ or, i could go away and get that extra letter from the bank, or come back on the exact date of renewal instead of a week in advance etc.etc.etc.
it was all explained to me in a friendly way, there was no demanding or aggression.
others i know, by asking if they could be helped and agreeing to pay extra fees have been able to gain extensions with less than the specified amounts in the bank, with less than the three months minimum time for the deposits to have sat in the account.
whether those extra fees are legitimate or not i cannot say, but it does sound as if there is a great latitude of flexibility as to when and how and if t's and i's are able to be crossed and dotted, at least in the day to day dealings of local immigration offices.