Lots of missing data

The vodacom balances view dissapeard on the website. When I clicked on the link it showed an empty page. It took a long time to come back. I checked regularly.When it come back over 13 GB of my data was missing. I am extremely careful of my data usuage and check up to 4-5 times a day to make sure my data last the month. Because of this loss I was not able to contact my loved ones or have imortant video meetings during a lock down. I called vodacom and I was told something is running in the background. All my apps setting dont allow automatic downloads. It turns out to be the phones system update that runs in the back ground-not updating just running that might have taken this data. If I was able to check my data this would not have happened and there is no setting to stop the update from wanting to install. I can only chose now or later. And it freezes my phone. All the back ground data is switched off and its still running taking data. I bought this phone from Vodacom. Vodacom must restore all my missing data asp, it's over R 900 to purchase the 13GB and that just not acceptable. Vodacon needs to replace my data urgently.