Hello. Many things can be said on the internet, however i'm going to assume you are legit, genuine and have done nothing wrong.

So in your first response back to blizzard you said you are using friends accounts to multibox? You get in trouble just for that if they look into it.

Secondly you made the same mistake I did which was just to respond to the tickets asking for them to double check-- without actually providing them with new evidence to support your claim. All that can happen there is they will review (which they did) and have only their information to look at again.

The account you used in the pictures you shared with us? GM's responding will literally just close it without reading from now on. You can try, but it won't do any good.

The good and bad summed up. You account share with friends (going by first image) and who is to say they didn't cheat. What if when you were investigated they were playing on their computers (with your charcters too) and they were doing something dodgy and it was independently verified by a GM. That's the bad.

The good news? If the accounts you used are on different battle.net accounts... you get more chances at having this reversed!
Jump on a second bnet account that was banned 'together', put in your case, give evidence to support YOU and they will review it again with your new information. If you can prove you didn't bot (by showing HOW/WHAT you multi-box in detail) and they can verify it on one bnet? they reverse the ban on all of them.

However if your friends botted and you used their characters later? no chance.
It also says you have only been banned for 6 months? that means whatever they did find wasn't too horrible by comparison.

Good luck.