Air time and data disappearing

<p>I am seriously considering changing networks after being an MTN customer for over 15yrs. I loaded airtime on my phone only for it to disappear. When I called MTN I was told it was on Internet. How is that possible when I have data on my phone. Am I not supposed to exhaust my data first before they can start deducting from my airtime. I really did not find any joy because I was told they can t explain what happened and will log an enquiry for investigation. Why is MTN *****ing from its loyal customers. My call reference number is ********** 71. This is not the 1st or 2nd time this has happened. I am really frustrated. </p>