Your house was placed into its band based upon a theoretical sale value, on the open market, on 1 April 1991. To get it re-banded you'd have to show that the figure which was used was incorrect. Given the passage of time, that could prove to be very difficult (unless, of course, you bought the house around that date).
The values since 1991 are completely irrelevant. To challenge a valuation (and the consequent banding), see here:
http://www.voa.gov.uk/news/information/your_co uncil_tax_band.htm
As that link indicates, your first battle would be with the Valuation Agency (which is completely independent of your local council). If you were successful in getting the property re-banded, you'd then be in a position to seek a refund from the council to whom you pay Council Tax.
Chris