MTN South Africa

Over a month ago now, I woke up one morning and overnight, 22 minutes of my time I pay for on my contract with MTN had 'disappeared'... despite many many phonecalls to mtn - an absolute waste of time, effort and resultant utter frustration with no answers - I then resorted to emailing various departments at mtn - all to no avail also. For some reason, there is no response from them - they will not give me a reason or explanation as to what happened to my 'lost' minutes... I have begun to think that maybe these minutes were '******' by an mtn employee who had access to my profile and contract and thought he/she could help themself and now this is being 'covered up'... I really hope this is not the case. But because I cannot justify what happened and they will not explain, I have been resorting to all sorts of possibilities. I am wondering whether anybody else has had a similar experience of losing minutes, and getting no service satisfaction or explanation?