DISAPPEARING DATA!!!!!!!

<p>I've got a data line with Vodacom which I don't use.I recently disovered that my data just disappears,now can someone tell me how on earth that happens if it's not an inside job?I never use that card so I wonder how long they've been doing this.The customer care department could not explain to me what happened to the data and just said that it disppeared!HOW CAN DATA JUST DISAPPEAR?????!!!!!!!WITHOUT ANYONE BEING ABLE TO TRACE WHAT HAPPENED????!!!!!!</p>