Why was I Banned?

I've just recently been banned, and I think it's completely unwarranted and over-the-top. I was playing draft pick as ADC, and someone wanted to ADC, so I gave it to them and switched lanes to mid. The game is going on, and they're losing. So I roam bot, asking them to engage with me at full health, and they refuse, which leads me to say they have no balls. Naturally, it would make anyone upset that you're being offered much needed help and refuse to take it. I don't think toxic is the proper term to describe my chat that game, or in any other. Never once have I used racial slurs, death threats, or told someone to kill themselves.

I'm not saying i'm completely innocent, but a ban is just out of hand. Chat restrictions would have been an acceptable punishment.