I'm troubled that your 18 yr old son was 1) intoxicated to begin with and 2) intoxicated at a party sponsored by the high school.
Since he was intoxicated (and to top it off, illegally drinking), you're not going to get any insurance company to cover this claim. As for the $3300 versus the vehicle's value, that would be something for a judge to decide in small claims court.
Why was your son drinking?!?!?!??!?!?!?!
