Where did my airtime go?

<p>So my airtime has been dissapearing. On thursday I had R20.00 airtime on my phone at which point I went on vacation to a game farm with no signal. On monday, After returning from vacation I attempted to make a phone call and was shocked to hear that I did not have sufficient airtime to make a call. When I checked my balance I only had R3.78 airtime left from R20.00. My question is: Where did R16.22's airtime vanish to?</p>