MTN Airtime disappeared.

My airtime that I had loaded disappeared on the morning of the loading of my monthly contract bundles. I went to bed on R9,58c airtime and my phone had not data switched on. Following morning my airtime balance was R1,09c and upon my enquiry via MTN Twitter account the person assisting me by the name of Presley told me there's no show of any deduction between 16th and 17th, and asked to check if I'm not subscribed to anything, which I'm not. Im just confused as to how do they not see where the airtime went to if it's not MTN who took my airtime. So dissatisfied with these antics.