So both your contractor and the insurance company contractor have said that the entire roof needs replacement? Have you asked your insurance agent or insurance adjuster why the insurance company is refusing to follow their own contractor’s assessment?
I suggest you continue to press for full replacement. You might even want a third independent contractor’s report to support the assessment of the other contractors. And you could contact an attorney in your area for, first, a review of your policy and the contractors’ reports and, second, to draft a letter to your insurer with a threat of legal action if the terms of the policy are not honored.