Airtime being used on Data WITH a data bundle

I received an alert last night at 20h32 stating my remaining data was at 4.88 MB - I immediately switched to my wifi and when I requested a detailed balance summary, I noticed that I was short R200 airtime (but still with data). I called 111 and requested assistance, I requested my balance again (note: I am connected to wifi) and my balance has gone down a further R38. <br> <br> I send an email to customer care and they call my dad for verification and fail to call me that evening. I receive the phone call from Vodacom today (after having to buy 50 MB data for the day) and have been advised that my airtime was used for data DESPITE still having data (in fact I still have 0.86 MB left since the alert at 20h32). I am now being told that the refund is not guaranteed (due to a pending investigation) and that I will need to purchase additional data with my own money (which means a smaller, more expensive bundle) until the investigation is complete. The call centre lady didn't even mind me posting on this platform - terrible customer service.<br> <br> This is unacceptable. My airtime should not have been used as my data bundle has yet to be depleted. I expect a FULL refund IMMEDIATELY.