How to follow up !? (Paris)

Hello,

I'd like to know if there is a certain way/procedure to follow up with a letter sent by me to these government offices in Paris,

1- Centre des archives du personnel militaire
Caserne Bernadotte
Place de Verdun
Protected content cedex
FRANCE

2-Service de la nationalité des Français établis hors de France
30 rue du Château des Rentiers
Protected content Cedex 13
FRANCE

It has been 2 months and I have not received any response, although the package has been received according to the courier.

Thanks, Paris Forum in advance.