samething happened to my dad

If your own insurance doesn't cover the expense, the only option is to sue him. He will loose the case, then you can legally collect from him. This can be a one-time payment or multiple deductions from his paycheck.

My dad got hit by an uninsured person a couple of years ago. In my dad's case, the other person was very poor, didn't even have a steady job. So eventhough we won, he didn't have anything we could collect. Luckily, my dad didn't suffer any health damage. He just had to eat the cost of the accident himself.

As for medical fees, it is a fixed price, cannot be haggled like in the farmers market.