Sorry for you

Long story short, I had 1GB of data on a brand new password protected router. 2 days later I'm out of data, brand new router says I've only used 320MB. Telkom sent me 'my' spreadsheet of used data. I apparently used the data when I wasn't at home (cctv footage to prove) with no devices on or connected. Router was even OFF! Magic? Then it shows I used data even though I was apparently out of data? Telkom's response, only after the manager didn't call me back and I had to use social media: sorry we can't help you. Our system is correct. (We can't/won't do anything further to help you). They may be cheaper than the other networks but be careful guys, maybe it's worth spending a bit more and getting what you pay for.