Vanishing airtime and No answer where it went

I loaded airtime on my mobile to get hold of someone, the call was 18 seconds. 2 hours later I tried to make another call and I was told my airtime was no more. I have been calling customer care for 2 weeks now, and no one can tell me where my airtime went to. I was told on the 27th it will take 48 hours to investigate, when I followed up, I was told it takes 7 days to investigate. Still no one is getting back to me with an answer.<br> <br> I have managed to get hold of 2 call center supervisors in Cape Town, of which they have not come back to me with an answer in over 5 days. The people handling social media do not seem to know how data is consumed on phones and try to be smart with an experienced IT professional.<br> <br> I just want to know what happened to my airtime and where is the customer service within MTN????