Disappearing airtime

I bought a R100 airtime through my standard bank app at 21:27 and my transaction was successful so i can buy a data bundle through MyMtn App which costs R99 for 7 days. When I went to MTN app to buy data bundle, I got an error message that I have insufficient funds. I further loaded a R20 from my Capitec App so I can cover any difference if there's any. But I couldn't buy the data bundle I wanted because the balance at that time was only R20 on both *136# and MyMTN App. And please note that I received smses from MTN indicating that my account has been topped up with R100 and R20 although this could not appear on my balances. I then phoned 135 at 21:36 to enquire about my predicament and I spoke to Bulelani Ngubelanga who then checked on the system and said to me that he can only see the balance of R20 but can't see the airtime that I said I loaded on my account. He then asked me to send him proof of payment especially for the R100, he then sent me his email address for me to forward the document. I then sent him the proof of payment at 22:22 using my computer. All this time I have using my WIFI. Pity Bulelani never came back to me regarding the disappeared airtime or if he received my email. I then called 135 at 00:06 to further find out what happened to my airtime, all I got was I am being transferred to the billing department of which I held my call for almost 30 minutes but couldn't get assistance. I then called 135 at 08:34 and what I got was unbelievable, I was told that my airtime was all used up by the internet, I mean R120 worth of airtime was all used up in a space of 5 minutes and at that time I was using WIFI, I only deactivated WIFI so could buy the data bundle. What is confusing me is that from the system not recognizing that I have loaded airtime to my airtime has been depleted overnight, I can't stomach that. Maybe I should move to Telkom and save myself from this, its very unprofessional.