Insurance claim

I had insurance cover for my office from a psu insurance company. There was fire in my office in which big quantity of cloth in my office got burnt. The insurance company sent a surveyor to verify the claim. The surveyor, acting arbitraly, submitted his survey report to the insurance company for only about 65% of the claim amount. The insurance company called me and offered me to settle the claim for 65%, as per surveyor’s report. which I declined. I filed a grievance against the surveyor and the insurer for not offering reasonable claim settlement. After which a meeting was kept between the surveyor, insurance company officials and myself in which all aspects of the claim were discussed. All parties in the meeting relented a bit and as a compromise, some points were agreed to and were written down in a “minutes of meeting”. Kind of middle path was agreed to in that meeting. After this meeting, the surveyor mad an addendum survey report and my claim assessed amount was increased to around 80%, as per the points agreed to in “minutes of meeting”. The surveyor mailed me the addendum report and asked for my consent, which I provided, after which the addendum report was submitted to the insurer. The manager of the insurance company offered me a discharge voucher for 80% of the amount as per the survey report, which I accepted. After all this, the insurance company went back on its promise to pay the claim and for discharge voucher that they had offered, they say that it was offered by mistake and thus they would not honour it. They keep on delaying my claim saying that they need to further study it. Please guide as to what should I do ?