"1. Sibling account was never approved. If it was we would have made a note of it - there is no note.
2. You are not allowed to share devices as a sibling anyway - you were.
3. 13.5 kpg for a new player? That is enough for us to assume you had part in your "sibling" account.
The ban stays.
Have a good night."
So if we only have one PC and the fact that my sister might be good at the game is reason to ban? Good to know.