Missing Airtime

I had R44.77 on my phone, bought power hour for R8 and balance was now R36.77. Made 3 calls, duration total is 60 mins and 11 seconds< which means I went over the power hour by 11 seconds. Now my balance is R23.42. Now I need Vodacom to explain if 11 seconds cost r13.35. I called the call centre and was told to wait for an hour for the system to update. After an hour they called and said I will be called this morning with feedback. Its now after 12, no feedback, airtime still missing and I wonder how long has airtime been dispearing like this. I'm really disappointed with the lack of feedback. I even wrote my complaint on Vodacom's facebook page this morning after 8, and it has not been published and still no follow up or feedback. This is poor customer service on top of the missing airtime Then when I call the service agent drops the call on me, just because I demand to know where my airtime is. She is telling about an app. Why must I download an app so that data can now disappear, just to check where my airtime is, and I have the call log and she has is too. I want my airtime and I must get pass your lack of feedback and the rudeness that you harbor in Vodacom call centres. I am beyond angry and disappointed. R13.35 might seem small to you but it's the principal of the matter and how long has this been happening. Vodacom please step up and explain.