Ramesh, Help me understand (since i have very low insurance knowledge), I believe the insurance is covering the vehicle right? As long as you have licensed driver and not drunk doesn't insurance should cover it?
On another point / a lesson to learn where drinking will crew your life. At-least take a cab/taxi if you are taking a drink.. Live better - Drive safe..
Happened to someone I know, the Insurance company (UA in this case) had a witness or multiple witnesses who cited the actual driver was different and was drunk.
The owner tried some semi-legal wrangling but UA did not budge.
If you're in the right though, fight by all means - you can go up the chain in the insurer, go to ombudsman, send a letter through lawyer that obligates a response with reasons.
Over here people wrap the whole car for paint protection. It's basically a clear vinyl. But it's quite expensive so only more exotic cars get the treatment. I don't see the point though, once the vinyl gets exposed to road grime, the car ends up looking weathered anyway. Proper wash/wax/polish and umtimately a respray over time seems more practical.