Insurance Claim Problem

[Kamakiri]

My question involves insurance law for the state of: Indiana

I was recently rear ended. The other driver was at fault and her insurance (State Farm) has agreed to pay for the damages. When the inspector came out, I told him that I was unsure if, but did not think that, some of the damage may have been prior (whoops). When I received a call of them about the claim, they stated that the prior damage is $600 to fix and the damage caused by their insured was $500. Knowing that nothing can be proven about any prior damage, I'm not going to fight over it. Per their estimates, there is $1100 worth of damage to my rear bumper. The person I spoke with said they are only liable for $100, being prior damage less damage caused. This seems very nonsensical to me, as it seems they should be responsible for the damage caused by their insured. Any help would be appreciated, as I'm unsure how to deal with this situation.

[lwpat]

You can sue the other person in small claims. This is pretty typical of State Farm.