Help i am getting ripped off by a car dealership and my credit is ruined?

i bought a car and obviously was ripped off. i am a single mother with little credit and it is being ruined by toyota of irving. i had the car for 4 months. the car was overpriced by 10,000. i signed the note and had full coverage insurance. the car was wrecked and the lienholder was paid but they are putting a chargeoff on my credit for 10,000. the insurance company says the car was priced way too high and i was ripped off help