You should discuss your coverages with your agent. They should have paid what the car was worth. Blue book value. This can be less than what is owed.
Always consult an attorney IMMEDIATELY as there are time limitations on filing a lawsuit.
Under your standard automobile policy, the carrier has to pay for the repairs to your car, or the fair market (book) value of your car if "totaled". If you took a loan out to pay for your car, that won't be covered unless you took out some form of "gap" insurance, which would cover the balance of monies owed on payments for a leased car or under a loan.
Search for a local car accident lawyer and discuss the injury and property reimbursement rules for car accidents. I believe you are saying you owed more on the total car than it was worth. In most states, property damage from a car accident is limited to the less of the cost to repair or the fair market value of the car. Check your car loan document for "gap insurance", providing coverage in this event.
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