No Nano SIM's in South Africa

I recently purchased a new cellphone that required a Nano SIM card. I am a current MTN customer and contacted their Centurion Mall, Mall at Reds and Melrose Arch branches on Monday 11 May to enquire whether they have SIM cards. None of them had stock. I then tried to call the national call centre (808) number, but the call is always dropped after holding a few minutes. On Wednesday the 13th of May I contacted the Centurion Mall branch again and was informed they have Nano SIM's. I drove there (a 20km round trip) and on my arrival was informed that they don't have SIM's and that MTN does not have any SIM's in their warehouse. I thus cannot use my new phone, cannot contact MTN other than through a branch and thus have no recourse. I cannot believe that MTN can find this level of service acceptable and hope to receive some response through this channel.