Assuming the chairman, vice chairman and clerk did not have specific delegated authority from the council to make changes to the poll, then they would have no right to do so.
Their action in carrying out a poll would not have the backing of the council and so any costs could not be laid at the council's door.
A formal poll is normally quite expensive, requiring the involvement of the local electoral authority, usually the district council.
Enforcement in any of these matters can be difficult, and will become more so when the Standards Board is disbanded.