I tried getting BA to issue an atw ticket originating in Windhoek by phone. The first segment was on BA operated by Comair. The BA agents were very polite, helpful, and happy to issue the ticket with a non-Namibian credit card. They even called me back several times about various details. But they charged the ex-South Africa price because BA has no issuing office in Namibia. The ticket is issued in South Africa at the South African price (in rand, not Namibian dollars) even though it originates in Namibia. The agents told me that they tried very hard to find a way to issue the ticket in Namibia, but it is not possible even at the airport. I suspect they have no issuing office in Maputo either, but I didn't ask.