My car is insured for a Total IDV of 680910.00 for 0 depreciation.
How come your IDV is with 0% depreciation. It should be with 5% depreciation?

Read -
How IDV(Insured's Declared Value) is calculated?

I have a claim of rs 436000/ for repairs from the company which is lower than 75% of value of insurance. The insurance Co is not sanctioning repairs but calculating total loss on salvage basis of rs 360000.00 for the car & are willing to pay 319910.00 as insurance value. Our argument is that we do not want total loss but as the repair cost is below 75% the car should be repaired. Can the Insurance Co. force you to accept their ruling?
No. It should be agreed between you and insurance company.

The negotiations depends on various factors -
1- Who is at fault
2- Evidence available about accident
3- Car condition after accident (repairable/non repairable)
4- Garage Estimate (more than or equal to IDV)
5- Surveyor's report (observations made by the surveyor)

Sometime it's hard to get the entire amount/IDV - because there are so many riders etc. So always Try & negotiate - ask for detailed calculations before agreeing on anything etc.

Source - First & Second