Vodacom - A bunch of *******

On 08.07.2018 I awoke in the morning to find that my data was totally used up, supposedly the previous night while I was asleep. The only thing that could have used my data while asleep is an update - but all my updates are set to happen on wifi only. So where did my data go? I called in and spoke to Ursula Ditsego, who said that it was probably a whatsapp update. I said that it wasn't. She forcefully said that it was. I explained that all my updates happened over wifi. She failed to listen to me and said that she will give me 250mb of data, but that it wasn't admission of guilt. LoL. On 09.07.2018, I get a call from her to say that there was internet usage and youtube. I was asleep. How is this damn possible? 511mb of my data was ****** by Vodacom.