Based on Internet information, the Office Congolais des Postes et Télécommunications (OCPT), a government agency of the Democratic Republic of the Congo, is responsible for managing .cd domains.
That's true. I have sent complaints to them as well but to no avail. They don't even provide the usual automated message informing the sender that they received the message. I think they simply don't care and don't want to bother with it.