Missing airtime

I recharged with R50 this morning and purchased 30 minutes Vodacom to Vodacom Minutes to use for today. After this purchase< my balance was R45.85 and started to make phone calls using my 30 minutes. My calls to the Vodacom numbers did exceed the 30 minutes that I had purchased, however they weren't that long that R45.00 airtime would be finished by this. And when I try to call the call centre, I just get an automated machine which tells me that I should send an email to *** which also bounces back stating that my email has not been allocated to a service agent. What is happening to the so called Number 1 cellular network provider????