unfair warranty claim rejection

My car had a problem with responding late when applying brakes and also the handbrake lights was on couldnt go off and was leaking water.. Upon inspection by a mechanic they found that the handbrake switch needs to be changed,the abs module as well must be replaced and the water pump must be changed.

I then told them to go ahead and ill deal with the insurance for warranty as they were complaining that 1ST for Women takes forver with approving claims and also forver in paying for claims which is i decided to have it repaired and ill deal with the iinsurance..At first i took it to VW centurion and their problem was also that 1st for women gives them issues in processing claims and cant have a car sitting at a delaier for a month waiting for a claim to be paid and reason i opted for the mechanic i went to was that his quote was almost 10k less compared to VW.

i then asked them to proceed with the repairs and i had my car back in ,ess than 72 hours.Now the insurance company tells me 18 Days later that they wont refund me because i repaired without them authorising that i can have the car repaired.. The reason i did what i did is because they take forver to approve a claim and forver to have the claim paid as well hence most mechanics the moment you mention waranty through insurance they complain that the car will be packed for long gathering dust while witing for approval and in my csr my wife using the csr to take our kids to and from school and couldnt afford to have them stuck on the road or them having no car for day while we waiting for approval.

i feel this decision is unfair ,if the components are covered why csnt they refund me the cost of replacing those components ..i honestly feel this is unfair,already this car is stressing me with issues after issues and now instead of getting peace knowing i have warranty i am also stressing.