well, actually French companies don't send so often greetings card, usually it's only for international contact, as the customs can be different, so they are quite relaxed about that. It's more about politness and something like "hey, remember us?"
So just need to say "Mon equipe se joint à moi pour vous souhaiter nos meilleurs voeux pour la nouvelle annee"
Anyway, that's always better when u understand what you write. Hope one day, you will manage it. ^ ^