My French financial institution (Sogecap) refuses to complete their part of French Form 5000 (mirror 1, mirror 2) a.k.a. CERFA 5000 and French Form 5002 (mirror) a.k.a. CERFA 5002. This prevents me from submitting Forms 5000 and 5002 to the Fisc (= French tax authority). I suspect they're simply too lazy to fill Form 5002 (or lost some records to do so).
What are my possible recourses?