In view of reports that the United Nations via the Organisation Stabilisation Mission in the Democratic Republic of the Congo (MONUSCO) is considering to withdraw the Rooivalk helicopters due to the high costs to the United Nations, what are the (a) detailed costs of the Rooivalk Helicopter Unit in the Democratic Republic of the Congo, (b) relevant details of the prices and/or costs that have been charged to the United Nations for refunds, (c) costs of the comparative Ukrainian MI-24 with which the United Nations wants to replace the Rooivalk helicopter and (d) associated risks to South African soldiers which form part of the Force Intervention Brigade soldiers if the Rooivalk helicopters are replaced by MI-24 helicopters?