Take airtime for no reason

<p>I had more than R110 left on my phone after i purchased a data bundle, i received a sms they have been charging me R2 a mb since 7am now my balance is less than R49 and i didn't phone or smsed anybody today. Still i don't know where my airtime went after a 5min call with the first agent i had to phone again still nothing to know where my airtime went. This is why i am changing my network</p>