I have an avis maintenance plan, Bought the car through avis fleet, at 53 000km, my 3d gear synchro gave problems, they wouldnt cover it due to my car being a little late for a service, (I was I'll and wasnt even driving my vehicle) what the $#percent@ do

I have an avis maintenance plan, Bought the car through avis fleet, at 53 000km, my 3d gear synchro gave problems, they wouldnt cover it due to my car being a little late for a service, (I was I'll and wasnt even driving my vehicle) what the $#percent@ does a synchro have to do with the motor, service? Its Wear and tear. Now taking my car in for a service and they wont cover my brake pads, windscreen wipers, wheel bearing, or synchro! IT HAS NOTHING TO DO WITH THE ENGINE IT IS WEAR AND TEAR! I want this sorted out, I paid for a maintenance plan, I want it sorted!!!!!!! Craziest part is the vehicle was bought through avis Fleet which means their quality of vehicles are absolute *******! I only have 69 000km on the clock! If this doesnt get sorted I WILL take this further!