Make the insurance company produce proof your friend was at fault. maybe hard considering the accident was over 4 years ago.
If they can prove fault
put it back onto your so called friend who pranged your car and did not tell you.
As your friend is bankrupt with little or no assets it would not be worth the insurance campnay pursuing your friend to far and they would probably drop it as it would cost more to pursue than it is worth.
If at same time down the track they do come back to you (legally I do not see how) at that point make an offer to settle with them.
Until they can prove you are liable (which I doubt they can) anything debt collectors threaten is only bullsh!t and can not affect your credit rating.
You have to be proven to be liable for a debt before non payment of that debt can affect you
