Won a series yesterday, but it's still not complete

Dear Riot, Yesterday I had game that was very hard for me. I dropped down to S3 (again) and now was on series to S2 with one "free win". I faced Yasuo as Vel'Koz. He slaughter me and mocking me. Then he became toxic as hell. I just muted him. Our botlane flame each other for losing lane. But in the end (about 40 minutes) we got it. And won. But EUNE gone down without previous warnings in that moment. I didn't even got post-game lobby. I couldn't even report Yasuo or honor our jungler. And my series still has "one free win". It's just feels not fair.