Hmm, it's a long since you were banned. Why haven't you posted the unban request until now?
At least your team were not in a disadvantageous situation judging from the screenshot, so to me it doesnt look like the usual "bah, game is lost, I'll stop playing". Still, you should upload the replay to show that you did indeed tell the others why you were going afk and that there was nothing in the game that might have made you want to not continue playing.
If you have the replay, please upload it on http://replay.garena.com and post the link in this thread. If you don't have the replay we cannot unban you, but perhaps we'll reduce the penalty a bit.