Airtime *****ers

I did a swim swam at Mtn branch in Highveld Mall Witbank.. When my swim swamp was done I noticed that an amount of over R60 of airtime has been taken from my simcard. I spoke to Shalom who was very rude to me insisting that I made a call on my fone to some number when that time my fone was off while day.. She is accusing me of lying. Customer service agent are busy *****ing peoples airtime and mtn not doing anything about it... Horrible service