Loss of data

I am really furious at the way my data just disappeared. I've been a loyal customer of MTN for years now but lately I'm not happy.

I bought 1.5 GB data in the early hours of the 17th September 2023 which is divided into 500 MB daily. Just after recharging 12MB was gone. Within a space of 3 minutes 350 MB was already gone. I did not download anything and my data saving mode is ON. Why do I have to lose so much data when I barely did much on my phone?