Like others have said, rito's report system is a numbers game. One extremely toxic game is exactly the same to them as one slightly negative game. I don't know your history, and it doesn't matter. You've reached a 14 day ban by being really toxic for a long time, being slightly negative for a long time, or a mixture of both. You've accrued a bunch of negative points, now you need to dilute them or cancel them out with a bunch of un-toxic games.
Think of it is way (but remember, I am making these numbers up): Imagine that you have played 100 games. In 75 of them, you were toxic. That means, in 75% of your games, you were toxic. Now imagine that If you reach 80%, you will be permanently banned. I don't want to do the math on how many games that would be in this hypothetical example, but you'd be close to the edge. In order to back away from the edge, you'd have to play a bunch of un-toxic games to dilute all those toxic games and lower your toxic:un-toxic games ratio.
Imagine you played 100 more games, but you were only toxic on the last you played. Now you have been toxic in 76/200 games or 38% of your games. That is much farther away from that 80%. Remember: I MADE THESE NUMBERS UP AS AN EXAMPLE!