Unfair Insurance claim rejection

The reason stated by the insurance company for rejecting my claim is not related to the actual issue for which I raised the claim. I applied for the insurance claim because the underbody of my car was damaged while driving on an uneven road. The claim was inspected by the insurance surveyor, and the repair or replacement was officially approved through email by Royal Sundaram Insurance. Based on this official approval, the required repair was carried out at the Tata service center. However, after the repair was completed and the final bill was generated, Royal Sundaram Insurance wrongfully rejected the claim by citing a reason that does not correspond to the actual damage or circumstances for which the claim was submitted. Since the claim had already been inspected and officially approved, I was not expecting the claim to be rejected at the final stage. I was therefore compelled to make the payment to the service center strictly UNDER PROTEST, as I do not accept or agree with the rejection of the claim. The insurance manager sent a wrongful rejection letter today. Shockingly, they have copy-pasted an old, closed claim number, PV01299915, belonging to the previous owner, instead of my live claim number, PV01340216. This clearly demonstrates the insurer's gross negligence and unfair trade practice. I have paid ₹75,036 under protest to the Tata Service Center today. Please investigate this matter immediately.