Data usage

On the 25th of September 2017 I used my phone as a hotspot for not more than 40 minutes. I was alone. I had loaded 1 GB of data just before and worked on e-mails. Most days this would not even use more than 300mb of data. Not only did I go through the 1GB of data, but used a further 5,98GB of out of bundle data. I immediately rushed to Vodacom and lodged a complaint. I always monitor my phone use closely and was quite upset. They said someone else might have used my wifi hotspot - impossible as I have a password and was alone and it was the first time I used my phone as a wifi hotspot. I phoned my IT guy and asked if it was possible that my computer ran an update using 6,98GB of data in less than 40 minutes. He said it was highly unlikely and that the latest update Windows 10 was running used about 2.1GB of data, but that the update doesn't run in one go. Vodacom would accommodate me as a one-time only offer whereby I would pay R148 in every R1000 of out of data bundle rate. This didn't happen. I received the full account this month of R4,264.79. Nobody contacted me or rectified my account which I know I didn't run up. Also, I never received the updates that normally warn you about your data use. I used my phone the morning at about 10 o'clock. At 13:00 about 20 sms's came through warning me of my data usage. I had stopped using my phone that morning after about 10:40 as a wifi hotspot. My service request number: 1- ********** **********