Future Generali India Insurance Company - Car insurance claim rejected

I have opted for comprehensive car policy from Future Generali India Insurance Company Limited with policy number. V*******. I have registered for a claim for accidental damage to my car and the claim no. for same is CM******. The damage is in the inner body of the car which is rear axle and damage is such which will not affect the car immediately but slowly will damage the tyres and suspension of the car.
Later on, one surveyor was appointed to inspect the car for damages. After a day, surveyor called the service centre where the car is parked and asked to send the photograph of the car as he said he is busy and cannot come for the inspection. Service centre executive sent the pictures of the car via Whatsapp. Next day, he told the service centre executive and to me that the damage is old rusted so it cannot be covered under the insurance. For the same, I gave him to detail that damage is not old and I took the car to the service centre after two days because that part is internal cannot be seen by the common man. I saw it because I went for alignment and balancing of the car. Then he changed the statement that the part is previously repaired. and he kept changing his statement.
For the same above, I raised multiple complaints in companies to call centre and also wrote email several times as a follow-up. On ** September, I received a hard copy letter from the company at my address stating that claim is rejected because in the claim form I have mentioned: “I was on highway and I stopped at a place for drinking water when I started again I hit a big stone which was lying on the road”. As per the letter damage happens due to mishandling at the time of discard of the vehicle from the occurrence place and not due to any perils covered under section * of the private car insurance policy which is as “The Company will not indemnify the insured against loss or damage to the vehicle insured hereunder and / or its accessories whilst thereon by accidental external means”.
My issues are:-
*) When surveyor did not inspect the car personally how he can determine the damages and conclude the statement that damage is old, repaired etc.
*) Upon complaint also I have not received any update from the company.
*) Surveyor is a third party and not a direct employee of the company.
*) After multiple follow-ups and emails also the company did not respond.
*) On rejection letter, the cause of the rejection is completely different as the cause which is told by the surveyor.
*) When I bought the insurance policy from the company no communication for terms and communication was made to me. Also, the policy document is never sent to me via e-mail or by hard copy mail to my postal address. How I will be aware of section * of the policy document as the policy documents is never sent to me also it is not in public forum.
*) What is the meaning of “Accidental external means” in section * of the policy and how it does not cover my cause? Big stone lying on the highway road in unexpected for public and when accidentally I hit the stone how it leads to mishandling.
*) The damaged part is rare part item and I am unable to get anywhere. Fortunately, that item was arranged by the service centre but because of insurance decline that part is not available more and my two tyres are damaged.
Request to please look into the matter as my car is getting damaged day by day because the part damaged effects the other part as well.