Vodacom uses airtime because data is finished

<p>Two weeks ago I dialed *111# for my detailed balance I had 150 minutes R65 and 4Gs of data. Today as I am trying to download a song I it was not allowing me to connect so I thought it was network. The problem persists and then I decided to go on Whatsapp and it was not allowing me to connect I then decided to check my detailed balance using *111# I see I have 85 voice minutes I have 40mb and R0 airtime balance. How can they use my airtime when I still had data how can they also use my airtime because sending me a sms to notify me that my data balance had been depleted Is this even legal can they do this? So disappointed in my service provider. Must one now not have airtime in the fear that it can be used with no warning . </p>