My car was written off and the insurer’s offer is much lower than expected

What you are owed depends on the type of cover. If you had agreed value cover, the insurer must pay the amount recorded in your policy schedule, whereas under market value cover, it must pay the market value of the car immediately before the accident, based on its age, condition, mileage and comparable sales. Ask the insurer for the valuation report and its comparable vehicles. You can challenge the offer by providing evidence of your own, such as recent sales listings of similar cars, service records, aftermarket additions and an independent valuation. Negotiate in writing, and if there is no agreement, escalate through the insurer's complaints process, then to an approved dispute resolution scheme, which can consider whether the offer was fair.