WTF I GOT BANNED????

I opened up my email today and they said I WAS BANNED FOR USING 3rd party software. I know that I am not that capable to be able to “hack” into such a sophisticated program that LoL is and I hope that this is a troll email. I am currently at school so I am unable to check if this is fake or not. :( also idk how to send photo lol. Also idk if this is weird but for some reason they sent the email to the email of my alternate account (not smurf), and not to the email that the account is registered to which utterly confounds me.