The jurisdiction where the accident occurred dictates laws relating to "at fault" issues. If SC, comparative negligence is the law. This governs your dealings with the "other" insurer, not yours. If you are dealing with your own insurer, percentage of negligence has no bearing. In the latter case, your own insurance policy, the collision coverage (subject to deductible), should pay generally for repair or replacement of like, kind and quality. The actual cash value (ACV) of your "R" (the replacement or "total loss" value) should be based upon the condition and mileage on your car. A couple quotes from the FAQ section in the Department of Insurance in SC website:
"3.Is South Carolina a no fault or at fault state?
South Carolina is a tort liability state, which means the not-at-fault person can pursue a claim against the at-fault party. South Carolina is also comparative negligence, which means you can be barred from collecting for the percentage you contributed to the accident.
11.Are there any specific time limits for an insurance company to pay claims?
In general, insurance companies should pay all claims in a prompt and reasonable amount of time. However, what constitutes "prompt and reasonable" may vary from claim to claim. Claims that require a special or extended investigation may take longer to resolve. Inclement weather conditions, coverage issues, and the number of vehicles involved in an accident can slow the process down.
13.Can the insurance company pay me less than Blue Book for my totaled vehicle?
Yes. The Blue Book is only a guide. The company is required to pay you what your vehicle was actually worth (as a used car) the moment before the crash. The adjuster will find out how much used cars like yours (same make, model, year, and mileage) are going for in your area. It's a good idea for you to independently research the value of your car too.
14.The adjuster recommended a specific body shop. Can I use a different shop?
You can have it repaired wherever you choose. But no matter what shop you choose, the adjuster will base your claim payment on market price for the repairs and pay the local average rates for parts & labor.
15.Who pays for the rental car while my car is in the body shop?
When the claim is against the other driver's company, the other driver’s company is required by law to reimburse your loss of use for what is reasonable and necessary. However, some insurers will do a direct bill with a rental car company.
If the car is totaled, many companies pay for your rental or reimburse you until a settlement has been offered."
See doi.sc.gov for more information, and/or to file a Consumer Complaint on line.
In any case, be pro-active on the handling of your claim. Minimize time lapses between contacts.
Hope this helps.