When the claims of the High Council, other than the contribution mentioned in II of Article L. 821-5 and the contributions mentioned in I and II of Article L. 821-6-1, have not been recovered amicably, proceedings shall be conducted in accordance with commercial practice or may be the subject of statements made enforceable by the Chairman. Enforceable statements may be notified to debtors by registered letter with acknowledgement of receipt. Debt collection is continued until the debt is contested before the competent court.