Have you looked at your contract? The excess is called la franchise and the exact amount will be written in the bumpf.
My franchise on the cars I have owned has been 300 euros for many years now. Perhaps yours is a bit higher as you do not drive the car all year round and you are sometimes an absent owner.
Have another close look, it should be plainly visible
Apprendre une langue, c'est faire un voyage différent chaque jour.
from Fle pour les curieux