Start by complaining to the company or organisation that sends the bill, keeping copies of messages and asking for a written response. For energy, you can usually take an unresolved complaint to the Energy Ombudsman after eight weeks or if you receive a deadlock letter; water customers in England and Wales can contact CCW. Broadband and mobile complaints may be referred to the provider’s approved alternative dispute resolution scheme. For council tax, contact your local authority first, and Citizens Advice can help you identify the correct escalation route and check whether support or discounts may apply.