A Rioter said season ends around 30th if I remember correctly.
Not sure if a "blackmark" stays on your account though after the ban itself is up.
I know for certain that people with a ban at the moment when the season ends cannot get it.
After Googling around, I think you are ineligible though.
EDIT: http://euw.leagueoflegends.com/en/page/2015-ranked-season-rewards
Yep, ineligible.
"Players banned for seven days or more in the three months prior to the end of the season (August 10) are ineligible for this year’s rewards."
So I assume the same would apply to this year.