This doesn't mean a thing, just because you have a hired period doesn't mean you didn't drive it outside this time, if the car was delivered to you there is nothing to stop you using it, this is not a good defence, you could easily have driven the car.
I had this once, what a pain in the backside. The obvious counter argument here would be- this is when I hired the car, you prove what time you delivered it.
I guess it depends on how much time you have to argue beforehand, but if you are that sure it wasn't you just opt for court and go from there taking any evidence you have to assist your case. Remember this is a criminal matter so the case has to be proved to a much higher standard than in a civil matter
As pointed out already it's important not to miss deadlines because you are no longer dealing with the hire company but the courts/police.
