And according to the excellent nav2000 site mentioned above, the numbers for closing flight plans are as follows:
CIV(cloture PLN) N° de téléphone
Reims - 03.26.05.03.08
Paris - 01.69.57.66.62
Brest - 02.98.44.79.63
Bordeaux - 05.56.55.62.53
Marseille - 04.42.96.49.31