That's entirely up to negotiation. They're not obliged to take any form of partial payment.
First, if the person trying to collect OWNS the debt, they aren't really a collection agency in the terms of the law. The FDCPA and much state regulation does not apply to them. If you are being contacted by the insurance company, they almost certainly are the one who owns the debt.
Second, Georgia doesn't license collection agencies. If they are an out of state agency, they need a certificate of authority, but frankly Georgia's laws on such are so friendly to the agnecies, there are many that operate nationwide from out of the Atlanta area.
You can try suing your uncle for the damages he caused, but if he doesn't have the money, you're going to have a hard time collecting even if you win.

