Insurance Hidden additional costs never disclosed to client nor seen in writting on acceptance of policy quote.

I took a car and household insurance with Omnisure and Aon brokers for Old Mutual. My policy states car rental of X amount of rands per day and Nil excess. I need to take my vehicle in and the car rental requests a deposit of R1500 to be returned # weeks after I return the vehicle? and should I end up in accident I need to pay a further R3500 excess. In my policy there are no additions to car rentals or refer to car rental additional say terms and conditions, nothing. Currently disputing with Omnisure and getting emails of extracts of only they have in their position which I was never issued with. Once accepted the policy any additional hidden extras should be to insurance co. account and not the client. Quick and cheap quote that keeps on escalating every time for no reason.