Bad service

I have two vehicles insured with Momentum STI ( Comprehensive with Car Hire ) and had an accident claim on the one vehicle . The damage was assessed and the vehicle was claimed as uneconomical to repair . Two options was offered , 1. Write off the vehicle and I get paid a certain amount and buy back the vehicle , 2. Repair the vehicle and we pay you an amount for the repair. I accepted the second option .As my policy has cover for Car hire whilst the vehicle is being repaired , I am told that it does not apply to me . When asked , "where it states that in my policy , I am told it does not as they can not add everything in a policy document. Why was I not told this when I signed and accepted the policy . Secondly , I have not been offered any advice/option as to the vehicle in question on current insurance options.