Permanent Ban with no explaination

I just found that my account has been permanently banned, and I'm really not sure why. I've been googling if any other players have ran into a similar situation and I sadden to find several players have had this or a similar situation and are still banned.

I've played since the start of season 3 and have never had any chat restrictions or bans. I tried to lookup anything I may have violated in the terms of use and can't find anything I've done wrong.

• I usually don't type in chat all the much since most the time I play with friends and use Curse/Twitch. Like I said, no chat restrictions or warnings. If I do chat, I always try to tell my team gj or ty, never anything negative. I would love to share my chatlogs with anyone to prove this if I could.
• The only third party programs I've used are Championfy and Overwolf. I've googled and found that these are approved by Riot. I have never used scripts, or would ever want to. I've always hated when game companies would let their games get filled with hackers and let them ruin the game for others (Go play any old Call of Duty and you'll see what I'm talking about). I'm glad that Riot is actively to protect the game from these types of players.
• I play at home on my home connection and on my phone's hotspot at work. At work I only play custom games so I never have to leave mid game. Is there any reason I could be banned for using a hotspot? I'm hoping this doesn't look as I'm sharing an account since I play from two different locations daily. (If you're wondering how I play at work, I work 3rd shift so work's super slow.)
• Can I be banned for leaving a custom game several times? While at work, I try to practice new champs in custom games and leave the games before I finish them so that they don't appear in my match history.
• I also saw that an account can be banned for a charge back on a purchase. I have confirmed that none of my purchases have failed to go through.
• The only time I've ever "left" a game is when my internet goes out. I always finish my games.

Other than these concerns, I can't think of a reason for my perma ban. It's really heartbreaking to have an account I've played on since the beginning for the past several years get permanently banned without any reason. It has pretty much ruined my night. I really hope someone from Riot Support can look into this for me. I've submitted a ticket a couple of hours ago, and I'm really hoping for response and resolution.

EDIT: Riot has contacted me and removed the ban. The ban was due to suspicious activity so they were just trying to secure my account. Thanks everyone for the help and advice!