Poor customer service MTN

Trying to cancel a Sim with MTN. I have tried on 3 occasions today to cancel a Sim with MTN. First time waited 28 minutes no response. Phoned again was transferred to the cancelation department waited 36 min no response. Phoned again waited 48 min still no response. Apparently there is no other method of canceling this Sim. Tried to speak to management but was told they are all busy with a call. Requested a call back but was told that they might get back to me by end of today. Why is it easy to speak to a champion consultant but nearly impossible to speak to someone who does cancelations. I would appreciate a response