There is no route to solving a problem of that kind that may not have unwanted repercussions. If the chairman is acting unlawfully, the option of court action exists, although it may be prohibitively expensive. If the council's financial affairs are being handled unlawfully, then a complaint to the external auditor is a possibility. If any councillor is obtaining pecuniary advantage from public office, then a complaint to the police is possible. If any councillor is breaching the council's code of conduct, a complaint can be made to the local Standards Officer. If any councillor is behaving badly in any way, it is possible to seek publicity through the local press etc. If vacancies arise, citizens can demand a poll to avoid co-option. At election time, citizens who disapprove of the actions of councillors can campaign against them - this is the ultimate solution and can certainly be successful. None of these routes is without difficulty though!