Vodacom- Airtime *******

I am a new Vodacom contract user. I've trusted Vodacom for many years. I've been hearing a lot of stories about airtime and data disappearing . Well, up until on Saturday that has never happened to me. I must say I'm extremely disappointed and upset that I too am now a victim of this. On Saturday 26 January when I got my contract phone, I was awarded 5 gigs of data, as promised, valid for 7 days. I have been very careful with the data. I have watched movies from Netflix, and was downloading them from the work Wi-Fi. Fast forward to Saturday the 2nd of February (on the day the data is due to expire). I used my data and have been consistently checking my balance. I decided to download songs, and some clips and movies from Youtube since I had over 3 gigs remaining. At 23h15, i once again checked my balance. It was on 829.02 MB and the airtime was R199.52. I have screenshots to prove this, exactly 20 minutes later, when i checked after downloading trying to download a song, i was told Ihave no internet connection. I decided to check the balance and it was on 0.00, including my airtime R0.00 ! I called their call centre, around that time 23h40. Their agent was really rude and helpful. Told me that I had too many Apps running in the background, and my data depleted at 23h28 which then consumed my airtime. In 13 minutes?? 829 MB gone? I called again, this time I was told that my data depleted while i was searching the internet. I asked exactly what I was searching, she couldn't say. She then advised me to go to "data ranking" and see what the data usage is. The data usage fro the entire week doesn't to equate to does not equate to 5GB: 2.19 GB for YouTube, 766 MB for Netflix, 531 MB for chrome, 139 MB for whatsApp, 68MB for Twitter, 66.47 Mb for Google Play Store, Google 41.90MB, Google Back Up Transport 16.43 MB, 14.38 MB for Facebook, 1.60MB for Weather Data Service, I have a screen shot to prove all this. I went to Twitter, I got ignored. I only got a reply after I asked again, and again I was told to monitor my balance in future...so who must pay for the airtime which they stole from me?? Because they will debit the money from my account.