How can I challenge my council tax band?

In April 2023 we bought a house that had extensive flood damage from a burst pipe. The house is rated in council tax band H, the most expensive tier, despite its condition. I sent the valuation team a list of similar properties and their lower band ratings in the road. In fact, my neighbour’s identical house is band G and they have done a loft extension with an extra bedroom. It is a lot of difference in money per year. The valuation team have decreed that it is the correct band as of April 1991. They said I can appeal. If I were to appeal, what kind of professional could assist me? Karen Benson

The modern council tax system was designed in a rush in